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I N T E R O F F I C E M E M O R A N D U M
Digital Equipment Corporation Date: 16-Feb-1997 20:42 AED
(Australia) Pty. Limited From: [email protected]
A.C.N. 000 446 800 "[email protected]"@US5RMC@ZPOVC@ZPOVC@MRGATE@SNOFS1@SNO
Dept:
Tel No:
TO: MUNSON BILL@A1@SNOFS1@SNO
Subject: Telecom Frequently Asked Questions File - 1997 Edition
From: David Leibold <[email protected]>
To: Telecom Digest <[email protected]>
Subject: Telecom Digest FAQ - revised edition
TELECOM Digest - Frequently Asked Questions - v.8 8 February 1997
* Frequency of Updates: approximately annual (special updates are possible)
* FAQ contributions to: [email protected]
or, [email protected]
or, [email protected]
Introduction...
This is a list of frequently asked questions made in the TELECOM Digest.
New versions of the list are occasionally made available to deal with new,
corrected or updated questions. Many contributors have made the FAQ what
it is today (those listed in the "Who contributed to this FAQ?" question
are hereby thanked).
Check the Archives...
Much of the telecom information that is requested can be found in the
TELECOM Digest Home Page, via WWW at:
http://hyperarchive.lcs.mit.edu/telecom-archives
This web page should have links to this FAQ file, as well as various
informational files on telecom subjects and the Digest itself. The
Archives for TELECOM Digest should also be available via the Home Page.
The TELECOM Digest Archives are also available through anonymous FTP at
massis.lcs.mit.edu (login as anonymous, mail address for password, cd to
telecom-archives). If possible, try to access the information via the
TELECOM Digest Home Page first. You can also access the Archives using
anonymous ftp at the mirror site: ftp.epix.net/pub/telecom-archives.
Also, there is an email <--> ftp service operating called the Telecom
Archives Email Information Service. Anything in the archives can be
obtained automatically by email. Send mail addressed to:
[email protected]
The subject does not matter. Include no text, sending just a blank
letter. You will get a help file by return mail and should use that
as a guide to ordering stuff by email from the archives.
A list of terms commonly used in TELECOM Digest is contained in a
"Glossary" section on the Home Page or in the Archives.
Try direct inquiries...
Direct netmail requests to persons posting on topics of interest to you may
also be helpful. In fact, doing things "behind the scenes" can be more
productive as the Digest Moderator is frequently swamped with other items.
Future editions of this list could include netmail addresses of contacts for
certain topics (say for ISDN, cellular, area codes/numbering plan, consumer
protection matters, etc.); offers to that end would be appreciated.
Where to contact the FAQ maintainer...
Suggestions for other common questions, or corrections or other amendments
to this file may be made to [email protected] (Fido
1:259/730) or [email protected] or [email protected]. Note that
any or all of these addresses are subject to change or discontinuance.
This file is updated approximately annually; special updates may be made as
time and circumstances permit.
Disclaimer Type Stuff...
All information herein should be considered subject to correction or
change. No endorsements or promotions of specific products or companies
are intended. Any specific references are made for example only, or in
order to adequately deal with certain subjects.
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List of subjects and questions covered as they appear in this list:
Technical
- How do phones work?
- What is a Central Office? What is a switch? What roles do Central
Offices and switches play in the telephone network?
- How many different types of switches are there, how do they differ,
and what switches are most commonly found in use?
- When did the first ESS (electronic) switch go into service?
- What frequencies do touch tones use for which numbers?
- What are the A, B, C and D touch tone keys used for? Why are they
not found on touch tone phone sets?
- The # key - what is it officially called? How many different names are
there for it? Why is it sometimes called a "pound" key?
- Can tone-operated services (voice mail, interactive voice response
sytems, etc.) be used by customers with dial pulse lines?
- What is call supervision?
- How can I find out what my own phone number is?
- Are there other kinds of test numbers used?
- Can a US modem or phone work in the UK, or some other European
country? (Or vice versa, or in general for international substitution
of phone equipment)
- What do "tip" and "ring" mean?
- Why use a negative charge (-48 volts) for Ring instead of a positive
charge (such as +48 volts)?
- What is "Caller ID" (or Call Display, or CNID (Caller Number
Identification))?
- How can I get specifications on how Caller ID service works?
- What is the best way to busy a phone line? I have a bank of modems
which are set up as a hunt group. When a modem dies I would like to
be able to busy out the line that is disconnected, so that one of the
other modems in the hunt group will take the call.
- What telephone wiring should be used?
- What is the difference between Caller ID/CNID and ANI?
- What is Switched 56?
- How does caller number delivery work on toll-free or extra-charge
services?
- Is there some way I can use a modem to send text messages to my
alphanumeric pager?
- How can I prevent an extension from interfering with a modem call?
Numbering
- What is a numbering plan?
- Who has authority over numbering plans?
- How was the country code system developed?
- What is the correct way to write a telephone number for
international use?
- What are the access codes used in international dialing?
- What does NPA, NNX, or NXX mean?
- What happens when all the telephone numbers run out in a given area?
- How long can a phone number be (internationally speaking)?
- What is Time T?
- What is an overlay area code?
- How was extra numbering capacity achieved in North America?
- In North America, why did long distance dialing within area codes
change so that 1 + home area code + number has to be dialed, or
change to just seven digits (like a local call)?
- What is an "interchangeable" area code?
- Why were "interchangeable" area codes introduced?
- Why not increase the number of digits in the North American
Numbering Plan?
- How will we make room if North American area codes are running out?
- What "interchangeable" area codes been assigned?
- What about expanding area/STD codes in other countries?
- How are area codes assigned?
- What is Bellcore?
- How can I contact Bellcore?
- How can I get exchange/billing data? What is a V&H tape?
- How are letters dialed? What was "2L5D"? What is All Number Calling?
Regulatory & Tariffs
- How are long distance call costs rated?
- What's this about the FCC starting a modem tax for those using
modems on phone lines?
- Why is a touch tone line more expensive than a rotary dial line
(in many places)?
- How come I got charged at a hotel for a call where no one answered?
Why is the timing on some of the long distance carriers inaccurate?
- What is AT&T Tariff 12?
- What are the ITU and CCITT?
Competition
- Which countries have competitive telecommunications services?
- What is a COCOT?
- What is an AOS?
- What is "splashing"?
- Where can I find a list of equal access (10XXX) codes?
- How can I tell who my default carrier is (or which carrier belongs
to a 10XXX+ code)?
- What is a LATA?
- Where can LATA maps be found?
Features
- What is the calling card "boing" and what is it made of?
- What are codes like *70?
- How can one dial *70 on a non-touch-tone (pulse/rotary) phone?
- How can I prevent the call waiting tone from beeping in mid-conversation?
- What is distinctive ringing?
Miscellaneous
- Is there a way to find someone given just a phone number?
- Who are the Telephone Pioneers?
- Where can a Cellular/Mobile Radio mailing list be contacted?
- How are VCR+ codes generated?
- What is CLLI?
- Why do movies often use 555-xxxx numbers? What does 555 represent?
- Are there cases of local calls across international borders?
- Which countries have freephone or "800" services?
- What is 'area code' 710?
- How can one call freephone numbers from other countries?
- Which World-Wide Web (WWW) sites have telecom information?
- What's an ObTelecom?
- Who contributed to this FAQ?
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---------
Technical
---------
Q: How do phones work?
A: A file in the TELECOM Digest archives under the name "how.phones.work"
is available and should explain some details of the workings of
the common telephone.
Q: What is a Central Office? What is a switch? What roles do Central
Offices and switches play in the telephone network?
A: A Central Office (CO) is the facility to which the telephones in a
public telephone network are connected. It is the gateway to the rest
of the telephone system; dial tone, telephone ringing, connection to
other telephones, long distance carriers or outside trunks, is done
here. Special features such as Call Waiting, Call Identification
("Caller ID") and voice mail can be provided at modern digital COs.
A "switch" is a general term referring to facilities where telephone
traffic is routed from one destination to another. The Central Office
has a switch in a local sense; calls within a municipality can often
be completed within a single switch. Beyond this, there are switches
for long distance or regional traffic, many of which are not directly
connected to user telephones.
A hierarchy of switching centres was developed in North America. Level
5 switches are the most common and are generally the local Central
Office switches. Level 4 switches are used in regional or larger local
settings and occasionally are connected to customer telephones. Level 3,
2 and 1 switches serve larger regions in turn. In general, a call that
cannot be handled at one level of switching (by reason of distance
covered, or congestion at a given switch) is passed onto the next higher
level until the connection is completed. The breakup of AT&T in the USA
and the introduction of new services will no doubt have disrupted this
hierarchy, but this illustrates how a call can progress from one place
to another.
A large city usually has many central offices, each serving a certain
geographical area. These central offices are connected to other central
offices for local calling, or to higher level switches, or into long
distance networks.
Q: How many different types of switches are there, how do they differ,
and what switches are most commonly found in use?
A: The original telephone switches were manual, operator-run switchboards.
Today, these are generally found in developing countries or in certain
remote locations as newer types of switches allow for connection to
automatic telephone service.
Step-by-step was the first widely-used automatic switching method. This
was an electro-mechanical system which made use of rotating blades and
mechanical selection of various levels. Dial pulses would be used to cause
the switches to select switch groups until the whole number was dialed.
Some step-by-step facilities still exist today, but will eventually be
replaced by more modern forms of switching (typically a digital facility).
Step-by-step, with its mechanical nature, can be difficult to troubleshoot
and maintain, and does not inherently support touch tones or special
calling features without special addition of equipment.
Step-by-step's "progressive control" could not be rerouted to avoid points
of congestion in the switches but was rather at the mercy of which numbers
would be dialed by the telephone users. There was also no capability to
select a variety of routes for the call. Different technologies were
developed to solve the inflexible routing problem, among other things.
Systems were developed where a "sender" could accept a dialed number,
then interact with a distant switch to establish an appropriate route
for the call to be completed. The concept of "common control" was
introduced: progressive customer dialing control would be replaced
by giving the central office the ability to determine the call's route.
The first common-control switches were developed by Western Electric
("Panel Type") and IT&T ("Rotary"). Panel Type switches used wipers
that moved vertically through contacts. Rotary equipment used wipers
that moved through contacts arranged in a circle. The two switches
were conceptually similar, to the point that switches of both types
could be directly connected. Most large U.S. cities used such switches.
Rotary switches were particularly popular in Paris, France, among
other places.
Crossbar was the next step in electro-mechanical switching. Rather than
the types of switches used in step-by-step or in Panel/Rotary, connections
were completed by means of a matrix of connectors, arranged in a grid.
The configuration of crossbar matrix elements was under "common control"
for routing calls.
Electronic switches (e.g. ESS) were developed in the 1960's. These were
often reed relay switches with an electronic common control faster than
previous crossbar systems. The fewer moving parts there were, the better.
Services such as call waiting or call forwarding would eventually be
possible under electronic systems.
Finally, the new digital electronic systems provide for a fully-
programmable telephone operation. These are all-electronic systems
which would process calls without moving parts (i.e. solid-state
switching) and full computerisation of control. Voice traffic would
now be converted to digital format for use with digital transmission
facilities. A wide variety of user services can be implemented such
as sophisticated types of call forwarding or Caller ID or ISDN
(Integrated Services Digital Network). Ultimately, all telephone
subscribers will be served by such switches as these.
Presently, various kinds of switching systems are in use, and the
proportions of what technologies are in use in given regions will vary.
The most common will eventually be the digital electronic systems.
There are significant costs associated with upgrading the network to
digital, fully-programmable switching, but the eventual goal of phone
companies worldwide is to modernise Central Offices and long distance
networks to such switches. In the meantime, the various switching
technologies in use must provide compatibility with each other in
terms of signalling among switches, call routing capabilities, and
the ability to use existing types of phone equipment.
Q: When did the first ESS (electronic) switch go into service?
A: In the U.S., the first 1ESS switch went into service May 1965 in
Succasunna, New Jersey. This was a software-controlled switch using
magnetic reed relays.
In Canada, the first ESS was set up in Montreal, circa 1967.
While there were substantial capabilities with such ESS switches as
1ESS or SP-1, these are being replaced by modern digital switches
(e.g. Northern Telecom DMS, Ericsson AXE).
Any information regarding international firsts in electronic or
digital switching would be welcome as a future enhancement to the FAQ.
Q: What frequencies do touch tones use for which numbers?
A: The touch tone system uses pairs of tones to represent the various keys.
There is a "low tone" and a "high tone" associated with each button
(0 through 9, plus * (star) and # (the thing that's called various names:
octothorp(e), hash, number sign, "pound" symbol). The low tones vary
according to what horizontal row the tone button is in, while the high
tones correspond to the vertical column of the tone button.
The tones and assignments are as follows:
1 2 3 A : 697 Hz
4 5 6 B : 770 Hz
(low tones)
7 8 9 C : 852 Hz
* 0 # D : 941 Hz
---- ---- ---- ----
1209 1336 1477 1633 Hz
(high tones)
When the 4 button is pressed, the 770 Hz and 1209 Hz tones are sent
together. The telephone central office will then decode the number
from this pair of tones.
The tone frequencies were designed to avoid harmonics and other problems
that could arise when two tones are sent and received. Accurate
transmission from the phone and accurate decoding on the telephone
company end are important. They may sound rather musical when dialed
(and representations of many popular tunes are possible), but they are
not intended to be so.
The tones should all be +/- 1.5% of the specified frequency. The high
frequency tone should be at least as loud, and preferably louder than
the low frequency. It may be as much as 4 dB louder. This factor is
referred to as "twist." If a Touchtone signal has +3db of twist, then
the high frequency is 3 dB louder than the low frequency. Negative
twist occurs when the low frequency is louder.
Q: What are the A, B, C and D touch tone keys used for?
Why are they not found on most touch tone phone sets?
A: These are extensions to the standard touch-tones (0-9, *, #) which
originated with the U.S. military's Autovon phone network. The original
names of these keys were FO (Flash Override), F (Flash), I (Immediate),
and P (Priority). The various priority levels established calls with
varying degrees of immediacy, terminating other conversations on the
network if necessary. FO was the greatest priority, normally reserved for
the President or very high ranking officials. P had a lesser priority,
but still took precedence over calls that were placed without any
priority established.
Today, the tones are commonly referred to as the A, B, C and D tones
respectively; each of these tones use 1633 Hz as their high tone. These
are found mainly used in special applications such as amateur radio
repeaters for their signalling and control. Modems and touch tone circuits
tend to include the A, B, C and D tones as well. These tones have not been
used for general public service, and it would take years before these
tones could be used in such things as customer information lines; such
services would have to be compatible with the existing 12-button touch
tone sets in any case.
Q: The # key - what is it officially called? How many different names are
there for it? Why is it sometimes called a "pound" key?
A: That key usually found under the 7 and to the right of 0 gets to be
called cross-hash, cross-hatch, enter, hash, noughts-and-crosses,
number-sign, octothorp(e), pound, pound-sign and no doubt other
names. There is some officiality to the term "octothorp(e)", spelled
with or without the 'e' depending on location or who you hear.
The term "number-sign" seems to be in common use for interactive voice
response systems, sometimes with an explanation that this button is
to the right of the 0.
As for the term "pound key", this might have something to do with the
# (number sign) in data being replaced by the UK Pound symbol in some
setups.
This topic was discussed in 1988 on the TELECOM Digest (Vol. 8, #190
with plenty of follow-up discussion) which should be available in
the FTP Archives.
Q: Can tone-operated services (voice mail, interactive voice response
sytems, etc.) be used by customers with dial pulse lines?
A: If a phone set has a switch between tone and pulse modes, it can.
Calls need to be dialed with the phone in "pulse" mode, where the
line is not set for tone dialing service. When the service is called
and is requesting entry of tones, switch the phone to "tone" mode
and proceed to enter tones as needed. On hang-up, make sure the
phone set is set back to "pulse" mode for the next call.
Q: What is call supervision?
A: Call supervision refers to the process by which it is determined that
the called party has indeed answered. Long distance calls and payphone
calls are normally charged from the time the called party answers, and
no charges should be assessed where the other end doesn't answer nor
where the called party is busy or blocked by network problems.
Q: How can I find out what my own phone number is?
A: If the operator won't read your number back to you, and if you can't
phone someone with a Calling # ID box, there are special numbers
available that "speaks" your number back to you when dialed. These
numbers are quite different from one jurisdiction to the next. Some
areas use 200 222.2222; others just require 958; still others 311 or
711 and others have a normally-formatted telephone number which can
be changed on occasion (such as 997.xxxx).
Such numbers exist in many countries; 175 is one number in the UK
while 19123 is one in Australia. There is no general rule for the
format of such numbers. These are normally assigned to codes outside
normal customer number sequences, however.
In areas where Caller ID is available, one could arrange to call
someone with an activated display unit and have that called party
read back the caller's number.
Q: Are there other kinds of test numbers used?
A: Yes. Again, space (and available information) does not permit a complete
list of what each telephone company is up to in terms of test numbers.
The most common number is a "ringback" or self-ring test number. When a
two or three digit number is followed by all or the last part of your
phone number, another dial tone occurs. Tests for dialing or ringing may
then be done. The ringback methods in some jurisdictions will vary.
Other numbers include intercom circuits for telephone company staff, or
switching centre supervisors, or other interesting tests for call
supervision or payphone coin tests.
One famous kind of test number belongs to NYNEX, the regional Bell
telephone company operating in the northeast U.S.A.. In New York at
least, there are "9901" numbers, or local numbers of the form xxx.9901,
which result in a recording which identifies the exchange represented
by the first three digits. The 9901 numbers may not necessarily exist
for all combinations of first three local number (central office code)
digits.
All these tests and services vary with each phone company; they are
not usually found in the phone book, needless to say.
Q: Can a US modem or phone work in the UK, or some other European
country? (Or vice versa, or in general for international substitution
of phone equipment)
A: Often it can, provided that the AC Voltage and the physical jack
are compatible or converted, and it can generate pulse dialing,
as many exchanges are not equipped for touch tone.
However, in most European countries it is illegal to fit non-approved
equipment. In the UK, approving equipment is the responsibility of BABT,
and the penalty is confiscation of the equipment plus a fine of up
to 2000 pounds sterling. Approved equipment has a mark, usually a
sticker, of a green circle with the words "APPROVED for connection
to the telecommunication system specified in the instructions subject
to the condition set out in them" and the number of the BABT
certificate. Non-approved items, if they are sold in the UK, must
have a sticker with a red triangle with similar wording except that
it's saying the exact opposite. It's perfectly legal to sell
non-approved equipment subject to the above, as there may be a
valid reason for using it, just not on the UK network.
In Canada, telephone equipment requires approval from the government
department known as Industry and Science Canada, or formerly through
the Department of Communications. Most equipment designed for American
conditions should be acceptable in Canada, and vice versa. A small
sticker indicating Canadian government approval is normally found
on approved devices.
Adapters have been developed to allow conversion from one national
standard to another. Electronics or telephone supply stores may have
such items. Whether these converters can legally be used in certain
countries is another matter, so buyer beware.
Q: What do "tip" and "ring" mean?
A: The conductors of a wire pair to a telephone set are referred to as
tip (T) and ring (R).. Tip (T) is usually positive charge with respect
to the Ring (R). Ring is typically at -48 volts (subject to voltage
losses). Tip (T) is then at ground when no current is flowing.
The actual voltages may differ in PBX/Key system situations (where 24
volt systems can be found) or higher voltages can be used for situations
where there are long distances among the subscribers and the switching
offices.
Two wires normally suffice to complete a connection between a telephone
and the central office; any extra wiring would be for purposes such as
as grounding, party line ringing or party line billing identification,
or even for dial light power on phones such as the Princess.
The Tip and Ring terms come from the parts of the plugs that were
used for manual switchboards.
In a U.S./Canada phone line, Tip is usually the green wire while Ring
is red. Black wire is Tip and yellow wire is Ring if a second line is
made from a four-wire cable. Colours and wiring rules will differ
according to country and according to what sort of wiring is being
done (punch-blocks, modular jacks, etc).
Q: Why use a negative charge (-48 volts) for Ring instead of a positive
charge (such as +48 volts)?
A: The reason for doing this is galvanic corrosion protection. A conductor
with a negative charge will repel chlorine ions, as Cl (chlorine) ions
are negative also. If the line were to have a positive charge, Cl ions
would be attracted.
This form of corrosion protection is called cathodic protection. It
is often used for pipelines, bridges, etc. Such protection was very
important in the days of open wire transmission lines.
Q: What is "Caller ID" (or Call Display, or CNID (Caller Number
Identification))?
A: This is a telephone company service that transmits the number of the
party to your telephone during the ringing. A data receiver detects
this signal and displays or otherwise accepts the number transmitted.
Whether or not a number is transmitted depends on political limitations
(some jurisdictions do not allow for Caller ID, or at least a fully
operational version of it) and technical limitations (e.g. calls placed
from older technology switches may not be identifiable; long distance
services may not be set up to provide end-to-end ID yet).
"Caller Name Display" is an extension of the Caller ID concept in that
the subscriber's name (according to phone company listings) is
transmitted. This may or may not be in addition to the Caller Number ID.
Q: How can I get specifications on how Caller ID service works?
A: The official documentation on how the Caller ID or calling line ID works
(in the United States at least) is available for purchase from Bellcore.
A description of what those documents are and how to get them is
available in the TELECOM Digest Archives file caller-id-specs.bellcore,
or see the question "How can I contact Bellcore?" elsewhere in the FAQ.
Local telephone companies may be able to provide technical information
for the purpose of providing equipment vendors with specifications.
Check the Archives for any other relevant files that may appear such as
descriptions of the standards and issues surrounding services such as
Caller ID.
In Canada, for information about the service (known there as Call
Display) contact: Stentor Resource Centre Inc, Director - Switched
Network Services, 160 Elgin Street, Room 790, Ottawa, Ontario, K2P 2C4.
(This address is changed from the one listed in FAQ #3 of 1992; note
that the title may be subject to change as well). Tel: +1 613 781.0534
(or 781.3655) or toll-free within Canada: 1 800 265.6608. The relevant
document is called "Call Management Service (CMS) Terminal-to-Network
Interface", Interface Disclosure ID - 0001, November 1989 (or likely
a newer version). The document used to be free, at least within Canada.
A charge (starting with CAD$50) was set by Stentor (the Canadian
consortium of major telephone companies) for this information. This
document deals with Bell Canada's Call Display standards, and may not
necessarily be fully applicable outside their service area (provinces
of Ontario and Quebec, parts of the Northwest Territories).
An electronic Caller ID construction project was part of the February
1994 edition of Electronics Now magazine (formerly Radio-Electronics).
In general, the North American Caller ID information is passed to the
telephone set in ASCII using a 1200 baud modem signal (FSK) sent between
the first and second rings.
In other nations where a Caller ID service exists, or is being
established, contact the appropriate telephone company for information.
Q: What is the best way to busy a phone line? I have a bank of modems
which are set up as a hunt group. When a modem dies I would like to
be able to busy out the line that is disconnected, so that one of the
other modems in the hunt group will take the call.
A: "Our modem lines all enter on RJ21 "punchblocks" so I've got some
rather nice clips that can be pushed over the terminals on the blocks
and make contact with the pair that I want to busy out. Between the
two terminals on the clip I have a red LED and a 270 ohm 1/2w resistor
in series. As long as I get the clip on the right way, it busies out
the line and lights up so I can see that I've got one of the lines
busied out."
"Since most of our modems have error correction, I've even gotten away
with putting one of these on a line that's in use -- when the user
disconnects, the line remains busy and I can then pull the modem at my
leisure. The modem's error correction fixes the blast of noise from
the clip as I slip it in."
- Brian
[Further notes [from Dan Boehlke]: A setup like this is not necessary.
For most systems simply shorting tip and ring together will busy out
the phone line. Some older systems, and lines that do not have much
wire between the switch and the point at which it terminates will need
a 270 ohm 1/2 watt resistor. The resistor is necessary because on a
short line will not have enough resistance to make up for the lack
of a load. Most modern systems have a current limiter that will prevent
problems. Older system may not have a current limiter and may supply
more current than modern systems do. In the followup discussion, we
learned that we should not do this to incoming WATS lines and other
lines that will cause the phone company's diagnostics centers to get
excited. A particular example was an incoming 800 number that was not
needed for a few days. The new 800 number was subscribed to one of
those plans that let you move it to another location in the event of
a problem. Well the AT&T diagnostic center saw the busy'ed out line as
a problem and promptly called the owner. -dan]
Q: What telephone wiring should be used?
A: This can be an FAQ file in itself. This will depend on the particular
nation as do-it-yourself wiring may not be legal in many cases, or may
require government-approved materials.
One aspect is the use of "Twisted pair", a cable where two wires twisted
about each other. This type of wiring has the advantage of reducing
"crosstalk" and other interference problems from external electrical or
magnetic sources. Twisted pair would be a better choice than straight,
untwisted "quad" wiring and also make possible modulation schemes that
allow for video transmissionn via phone lines (e.g. the ADSL standard).
Q: What is the difference between Caller ID/CNID and ANI?
A: Caller ID or CNID or Call Display refers to a service offered to
telephone customers that allows for display or identification of
telephone numbers from which incoming calls are made. ANI, or
Automatic Number Identification, refers to operations within the
telephone network that allow for the registering of a long distance
caller's number for billing purposes and not a public offering
as such.
Special services such as incoming number identification for
toll-free or premium program lines (800 or 900 service in
North America) make use of ANI information and pass this
along to the called party.
Q: What is Switched 56?
A: This is a data circuit operating at 56 kb/s that is "switched", or set
up to allow the customer to dial up other Switched 56 lines.
An "unswitched" connection (or "dedicated" or "leased") might be a direct
link between company offices, but not directly accessible from other
points in the general telephone network.
Since much of the regular voice telephone network uses a digital data
stream, Switched 56 delivers a data connection to the customer from the
telephone company's switch rather than an audio connection. A Switched 56
connection is useful for data and limited videoconferencing applications,
since it carries data faster than even the v.34 modem standard.
ISDN does the same job as Switched 56, plus other features. Switched 56
may be available where ISDN isn't, however. Each location using Switched
56 will require special units.
The BYTE Magazine of November 1993 contains an article comparing
Switched 56 with other forms of phone service.
Q: How does caller number delivery work on toll-free or extra-charge
services?
A: The ANI (Automatic Number Identification) feature for toll free (800/888)
or recorded/premium services (900) in North America predates the current
Caller ID/CCS7 signalling methods. The caller's number could be delivered
in terms of signalling tones (MF or multifrequency tones) included with
the signalling tones used to set up the call to the 800/888 or 900 number.
As for the precise method of delivering the number to the called 800, 888
or 900 party, and more details on 800/888/900 ANI, the answer will need to
wait for a future edition of the FAQ, or for a discussion in the Digest.
Again, ANI was in service before caller ID and its equipment were
commonplace.
Toll-free service customers can receive a list of calling numbers as part
of the billing arrangements. This is only a monthly summary long after
the calls were made, though, not a real-time caller number delivery.
Q: Is there some way I can use a modem to send text messages to my
alphanumeric pager?
A: (courtesy J. Brad Hicks ([email protected]))
You will need two things:
(1) The phone number of the modem lines at your paging vendor. Keep
pestering them until they let you talk to a real linesman or
engineer; if they support text pagers, it's guaranteed that there
is such a number.
(2) A piece of software that supports the IXO/TAP protocol.
There are a number of IXO/TAP software packages on the market. If you
want to write your own, the protocol specification is in the Telecom
Archives as IXO.TAP.protocol, along with some example code in HyperTalk,
ixo.example.
Q: How can I prevent an extension from interfering with a modem call?
A: Modem connections are very sensitive to any sort of interference,
including an extension that is picked up during a connection. The
usual result is the loss of modem carrier, thus the end of the
modem call.
There are some recent Northern Telecom phones that have a light to
indicate a line in use. While this will warn other extensions that
someone else is on the line, it doesn't physically prevent an
interruption on the used line.
Physical disconnection of extensions could be attempted; switches
in the wiring is one way to do this, as long as one remembers to
switch the extension off when making a modem call, and to switch
it back on when the line is available.
The deluxe solution to this problem involves installing a PBX system.
That way, each extension has a separate connection to the PBX first,
before any extensions get to the outside line(s).
Devices such as the RS Teleprotector or other extension lock-out units
can be connected into the phone wiring to provide an automatic means
of preventing line interruptions.
Q: How does one maintain a phone call when hanging up on one extension,
to pick up another extension?
A: The old PBX/key system feature called Hold is the way to maintain the
call on the line while switching from one extension to another. The
first extension is put on hold, then the other extension is picked up
to continue the conversation.
Assuming one doesn't want to spend much cash on an entire PBX system,
a few residential phones on the market may have a "hold" feature. Old
key telephone sets certainly will (if one finds the means to connect
these types of phones into ordinary phone wiring).
---------
Numbering
---------
Q: What is a numbering plan?
A: This is a plan which establishes the format of codes and subscriber
numbers for a telephone system or other communications system such
as Telex. On a local level, subscriber numbers can have a certain
number of digits (in some cases, the number of digits varies according
to the exchange centre or digit sequence used). The local plan would
allow for codes used to reach operators, directory assistance, repair,
test numbers, etc. On a regional or even national level, there need to
be area codes or number prefixes established in order to route calls
to the appropriate cities and central offices.
The typical pattern is to use local numbers within a region, and use
an STD (subscriber trunk dialing) or area code to call a number in
another region. The most common method worldwide is to use numbers
beginning with 0 as a long distance or inter-regional access digit,
followed by other digits to route to the proper city (e.g. within the
UK, dial 0171 or 0181 for London, or 0121 for Birmingham). Digits other
than 0 (generally 2 through 9) would then represent the initial digit
of local numbers.
In France, starting October 1996, all numbers were standardised to ten
digits domestically. 0123456789 would be a Paris number, for example.
Regardless of whether the call is local or long distance, the whole
10-digit number will be dialed. The new numbers were formed from the
previous numbering plan that was based on 8-digit local numbers and two
zones: Paris (area code 1) and outside Paris (no area code). The first
digit of the new numbers would always be 0. The second digit would be
an area digit e.g. 1 for Paris, 3 for Northeast. The remainder of the
new number would be the old 8-digit local number.
Some countries do not use an area code; instead, the local number is
unique within the country. This typically occurs in small nations but such
schemes are found in Denmark and Singapore. Hong Kong got rid of its area
codes at the end of 1989 and converted to seven-digit local numbers, which
subsequently became an expanded 8-digit local number system in 1995.
North America uses a fixed-length numbering plan. Area codes always
have three digits and local phone numbers seven. A separate '1' prefix
is dialed for long distance calls (that is, 1 + area code + number).
Mexico has variable length area codes, but the total number of digits in
the area code and local number is a constant 8 (e.g. Mexico City area
code 5 + 7-digit number, or Ciudad Juarez area code 16 + 6-digit number).
'91' is the standard direct dial prefix within Mexico (e.g. long
distance within Mexico is dialed 91 + area code + number). There are
reports that the numbering plan in Mexico will be expanded in the future.
Some nations such as Germany have an almost unpredictable variability
in area code and local number length. The number of digits in local
numbers can vary even within an area code. Direct dialing into PBX
systems there means a number can reach a main switchboard, but
dialing the number with extra digits would reach the extension.
Many countries include the prefix in their STD codes listing (0121
Birmingham, UK; 90 Helsinki, Finland (changed to 09 in 1996)).
Including the initial 0 or 9 may be convenient domestically, but these
numbers have to be omitted when numbers are dialed from other nations.
Q: Who has authority over numbering plans?
A: This is up to each country; in those nations with a monopoly telephone
carrier, this could be administered by the telephone company or a
government agency (noting that in many cases, the telco is a government
agency anyway). In those nations having competing carriers, governments
tend to set the rules, if not administering the numbering resources
themselves.
In the United States, the Federal Communications Commission (FCC)
oversees American telephone numbering and has ultimate authority.
Original area code assignments and numbering plan structure were
devised by the original AT&T monopoly system.
Following the break-up of AT&T, Bellcore (a non-governmental company
owned jointly by the major Bell Regional Holding Companies) assigned
the area codes and assumed duties as the North American Numbering Plan
Administrator.
Bellcore recently advised the FCC that it would relinquish its role
as the North American Numbering Plan Administrator. In its place is
to be an industry oversight organization consisting of various
telecommunications interests. This move is intended to avoid the
impression that numbering plan decisions are controlled by a particular
segment of the telecommunications industry.
In the United Kingdom, Oftel is the organisation responsible for
numbering plan issues. The "Phoneday" arrangement, where the digit
'1' was added to geographic area or STD codes, was an Oftel decision.
Industry Canada (formerly Communications Canada) is the government
agency having ultimate legal responsibility over the Canadian numbering
plan, which for all practical purposes is the adoption of the North
American Numbering Plan. A Canadian Numbering Administrator maintains
and co-ordinates numbering assignments such as long distance carrier
codes in co-ordination with the North American Numbering Plan
Administrator (i.e. Bellcore as of early 1997).
In Bermuda and those Caribbean nations under the North American Numbering
Plan, Bellcore has been the authority for telephone numbering assignments
within the original 809 area code territory. However, area code splits
such as the one assigning NPA 441 to Bermuda allows the individual
nations to assume numbering administration. This generally appears to
be the case as the individual islands in the Caribbean and Atlantic
now have separate area code assignments.
Q: How was the country code system developed?
A: In the early 1960s, a global numbering plan was devised so that the
various national telephone systems can be linked; this used country
codes of one to three digits in length, assigned according to geographic
regions on the Earth. In fact, the system was developed from a numbering
plan already devised for Europe. International Telecommunications Union
(ITU) documents from that time showed a numbering plan of two-digit
country codes covering Europe and the Mediterranean Basin countries and
even described at that time the overseas access codes to be used in
various countries (France 19, UK 010 - most of these codes were in use
for many years thereafter). Many country codes from that original
numbering plan were used in the worldwide plan such as France 33,
UK 44 although many codes had to be renumbered for the new worldwide plan.
The world numbering zones (representing the initial country code
digits) are:
1 North America
2 Africa
3 and 4 Europe
5 South/Latin America (includes Mexico)
6 South Pacific countries, Oceana (e.g. Australia)
7 Commonwealth of Independent States (former USSR)
8 East Asia (e.g. Japan, China), plus Marisat/Inmarsat
9 West & South Asia, Middle East (e.g. India, Saudi Arabia)
There are a few anomalies to the zoning; St Pierre & Miquelon, a French
territory near the Canadian province of Newfoundland, was issued a
country code in zone 5 (country code 508), since North America already
has the country code 1, and there were no codes available in zones 3 or
4 (at the time of original assignment). There was room in world zone 5
for the code. Similarly, Greenland (country code 299) could not be fitted
into the European zones. 299 was a code that was available from another
zone (Africa) that was numerically close.
ITU-T policy is that new country code assignments will be three digits.
Country codes for new types of international services, such as toll-free
country codes, are to be assigned from the world zone with the most
unassigned country codes (currently zone 8, meaning special services
will have country codes beginning with 8). There is some talk of
assigning the available country code 800 for an international toll-free
service (though this might be confused with national toll-free services
that already use an 800 area code).
The TELECOM Digest Archives has country code listings, including a
detailed set which indicates area/STD codes used within country codes
as they would be dialed in international dialing (excluding domestic
inter-regional prefix digits).
Q: What is the correct way to write a telephone number for
international use?
A: The method recommended by the ITU-T (formerly CCITT) is set forth in
Recommendation E.123. International format numbers use the plus sign
followed by the country code, then the STD code if any (without common
STD/area code prefix digits or long distance access digits) then the
local number. The following numbers (given for the sake of example
only) describe some of the formats used:
City Domestic Number International Format
--------------- ----------------- --------------------
Toronto, Canada (416) 872-2372 + 1 416 872 2372
Paris, France 01 33 33 33 33 + 33 1 33 33 33 33
Birmingham, UK (0121) 123 4567 + 44 121 123 4567
Colon, Panama 441-2345 + 507 441 2345
Tokyo, Japan (03) 4567 8901 + 81 3 4567 8901
Hong Kong 2345 6789 + 852 2345 6789
In most cases, the initial 0 of an STD code will not form part of the
international format number. Some countries use a common prefix of 9
(such as Colombia, and formerly Finland). Some countries' STD codes can
be used as they are where prefix digits are not part of the area code
(as is the case in North America, Mexico, and a few other countries).
As indicated in the above example, country code 1 is used for the
U.S., Canada and many Caribbean nations under the North American
Numbering Plan (NANP). This fact is not as well-publicised by American
and Canadian telephone companies as it is in other countries. Note
that 1 is dialed first in domestic long distance calls; that this is
identical to country code 1 is a coincidence.
The important consideration is that the digits following the +
represent the number as it would be dialed on an international call
(that is, the telephone company's overseas dialing code followed
by the international number after the + sign).
Q: What are the access codes used in international dialing?
A: This depends on the country from which an international call is placed.
The most common international prefix is 00 (followed by the international
format number), which most countries have adopted or are planning to
adopt. An ITU-T Recommendation specifies 00 as the preferred code. The
European Union nations in particular are adopting 00 as the standard
international access code. Those EU nations not already using 00 will
soon do so.
Toby Nixon of Microsoft ([email protected]) maintains a full list of
these international access codes. These are occasionally posted as Digest
articles (with a recent posting being in Digest v15 #480).
Some of the current or recent exceptions to 00 are:
Australia @ 0011 Norway @ 095
Canada 011 Papua New Guinea 05
Colombia 90 Russia 8 W 10
Denmark @ 009 Singapore 001
Japan 001 Spain @ 07
Mexico + 98 Sweden @ 009
Nigeria 009 USA 011
W = wait for another dial tone before proceeding with rest of number
+ = Mexico uses 95 to access North America (country code 1) specifically;
98 is used for calling other nations
@ = Indicates reported plans to switch to 00 within a few years,
if not already.
Finland: The standard 00 access was added 12 October 1996. However,
990, 994 or 999 may also be used depending on the carrier desired.
00 is intended for dialing through a contracted "default" international
carrier.
Former international access codes:
- France was 19 W until recent conversion to 00
- Ireland was 16 until conversion to 00
- Netherlands was 09 W until its recent conversion to 00
- Romania recently overhauled its numbering plan, converting to 00
for international access in the process
- Singapore had 005, but converted to 001 rather than 00
- Turkey replaced its old 9 W 9 international access with 00
- United Kingdom adopted 00 as the international access code in 1995,
replacing the 010 access code
Q: What does NPA, NNX, or NXX mean?
A: NPA means Numbering Plan Area, a formal term meaning a North American
area code (like New York 212, Chicago 312, Toronto 416 etc.).
NNX refers to the format of the telephone number's prefix or central
office code (the first three digits of a seven-digit local North
American number). The N represents a digit from 2 to 9; an X represents
any digit 0 to 9. Thus, NNX prefixes can number from 220 to 999, as
long as they do not have a 0 or 1 as the middle digit.
NXX means any prefix/central office code from 200 to 999 could be
represented, allowing for any value in the middle digit. Obvious special
exceptions include 411 (directory assistance) and 911 (emergency).
Q: What happens when all the telephone numbers run out in a given area?
A: With demand for phone numbers increasing worldwide, the capacity given by
a certain number of digits in a numbering plan will tend to be exhausted.
In whatever country, capacity expansion can be done by such measures as
adding an extra digit to the local number (as was done in Tokyo, Japan
or in Paris, France). Area code numbers themselves could also have extra
digits added to increase the number of available area codes. See also
the following question on "overlay" area codes.
Area/STD codes can be split along geographic lines, such as London UK's
split of the old 01 STD code into 071 (inner London) and 081 (outer
London). These codes are now 0171 and 0181 respectively, as a result
of yet another UK numbering change called "Phoneday".
Q: How long can a phone number be (internationally speaking)?
A: Internationally, telephone numbers may currently have up to 12 digits
total for the combined country code, area code, and subscriber number.
That is, an international call at present should have no more than 12
digits after the international dialing code.
The maximum number of international number digits limit will be increased
to 15 digits total as of "Time T" (end of 1996), to allow for extra
numbering capacity within countries, and to expand the numbering capacity
for international calling.
Some telephone numbers in Germany, for instance, are reported to exceed
the current 12 digit international limit already. A few other countries
may also have telephone numbers that exceed the current international
maximum length. Such numbers may require manual operator handling in
areas where switches are not already capable of doing so.
Q: What is "Time T"?
A: 31 December 1996, 2359 hours UTC (GMT), as referred to by ITU-T.
Q: What is an overlay area code?
A: An "overlay" area code is assigned to serve as a parallel code in an
existing area code's territory. Cellular and pager services, for
instance, could operate with an overlay area code distinct from the
geographic (traditional phone service) area code(s) used in the region.
Furthermore, many area code boundaries are becoming too small to
practically subdivide in terms of geography.
Overlay area codes are being implemented in the United States for
dedicated use by cellular and pager services. Los Angeles originally
had the 213 area code, and subsequently divided this territory with
the 818 and then 310 area codes. Now, a new 562 area code will be
the first overlay for this territory.
Q: How was extra numbering capacity achieved in North America?
A: Within an area code, there are a maximum number of prefixes
(i.e. first three digits of a phone number) that can be assigned.
In the original telephone "numbering plan", up to 640 prefixes
could be assigned per area code (of the NNX format, 8 * 8 * 10).
Yet, prefixes get used up due to growth and demand for new numbers
(accelerated by popularity of separate fax or modem lines, or by
new services such as the distinctive ringing numbers that ring a
single line differently depending on which phone number was dialed).
When the prefixes of NNX format run out, there are two options
in order to allow for more prefixes, and in turn more numbers:
1) "splitting" the area code so that a new area code is
assigned to accommodate new prefixes, or
2) allowing extra prefixes to be assigned by allowing NXX
format instead of NNX format.
The preferred option is to go with 2) first, in order to avoid having
a new area code assignment. Yet, this gives the area code a maximum of
160 new prefixes, or 8 * 10 * 10 = 800. When the NXX format prefixes
are used up, then 1) is not optional. New York and Los Angeles are two
regions that have gone from NNX to NXX format prefixes first, then
their area codes were split.
Interestingly enough, some area codes have split even though there was
no change from NNX format prefixes to NXX at the time. Such splits have
occurred in Florida (305/407) and Colorado (303/719). The precise reasons
why a change to NXX-style prefixes was not done in those cases were not
known, but switching requirements in those areas, plus telephone company
expenses in changing from NNX to NXX format (and the likelihood of an
eventual area code split) were likely factors in these decisions.
Note that it is prefixes, and not necessarily the number of telephones,
that determines how crowded an area code is. Small exchanges could use
a whole prefix for only a few phones, while an urban exchange may use
most of the 10 000 possible numbers per prefix. Companies, paging, test
numbers and special services can be assigned their own prefixes as
well, such as the 555 directory assistance prefix (555.1212).
Q: In North America, why did long distance dialing within area codes
change so that 1 + home area code + number has to be dialed, or
in some places change to just seven digits (like a local call)?
A: Originally, most areas of North America allowed long distance calls to
be dialed as 1 + area code + number for calls outside an area code,
while calls within an area code could be dialed as just 1 + number. A
distinction between area codes (having 0 or 1 as the middle digit) and
prefixes (middle digit cannot be 0 or 1) made this possible.
When prefixes change to NXX, that means that the prefix numbers can be
identical to area codes. The phone equipment is no longer able to make a
distinction between what is an area code and what is a prefix within the
home area code, based on the first three digits. For instance, it is hard
for central offices to tell the difference between 1+210 555.2368 and
1+210.5552, based on the first 8 digits dialed.
Thus, 1 + area code + number for all long distance calls is used in
many North American area codes. Or ... just dialing seven digits within
the area code for all calls, local or long distance (thus risking
complaints from customers who thought they were making a local call when
in fact the call was long distance).
To make room for more area codes, all areas in the North American
Numbering Plan (NANP) made allowances in their dialing schemes for
new "interchangeable" area codes (see following questions). The
distinction between the area code and prefix (central office code)
formats was lost for all area codes as of January 1995.
It is up to each phone company to decide how to handle prefix and
dialing changes. There are different rules from company to company.
Q: What is an "interchangeable" area code?
A: The interchangeable area code format refers to area code numbers that
can be the same as prefix numbers. In other words, the new area codes
with middle digits other than 0 or 1 are "interchangeable" in the
sense that the area code and prefix numbers can now be the same.
Q: Why were "interchangeable" area codes introduced?
There were a limited number of area codes available under the original
North American format. Just prior to 1995, there were no longer any area
codes that could be assigned from the traditional format other than a
few special "non-geographic" codes (200, 300, 400). Some other special
cases include 600 for Canadian Datalink/ISDN service, which began as the
Canadian TWX (telco teletype) code. 600 was formerly 610, which is now
in use splitting area 215 in the Philadelphia area. 710 is reserved for
mysterious U.S. government services.
Area codes ending in -00 are intended for special services like 800 or
900 numbers. Also, -11 area codes could be confused with services like
411 (directory assistance) or 911 (emergency); indeed, a few places
use the non-standard 1+411 for directory assistance.
Bellcore, while it was North American Numbering Plan (NANP) Administrator,
set the January 1995 date at which interchangeable area codes were to
become active. Given the unprecedented demand for new area codes,
the original interchangeable deadline of July 1995 was a good guess
when it was announced many years ago.
The last vacant traditional-format area codes were 910 (split North
Carolina's 919 area code) and 610 (Pennsylvania, split 215 Philadelphia).
For some time, the plan was to assign new area codes that end in 0 (such
as 220, 650, etc.). This would have allowed some area codes to retain the
ability to dial 1+number (without dialing the home area code) for long
distance calls within the area code, provided that they have not assigned
prefixes ending in zero in conflict with new area codes. That scheme
appears to have been abandoned in favour of assigning area codes with
various third digits.
Q: Why not increase the number of digits in the North American
Numbering Plan?
A: Some have suggested that the local numbers in metropolitan areas have
8 digits rather than keep the 7-digit format and force the assignment
of numerous area codes.
The expansion plan for the NANP was set in the 1970s, if not earlier. The
planners probably thought that keeping the area code and local number
digit lengths was less disruptive and expensive compared to changing the
length of the local number and/or area code. A uniform total number of
digits in the area code and local number was probably thought desirable,
also. The advent of interchangeable area codes means a huge increase in
the number of available area codes, which should allow growth in the NANP
for many years yet.
Still, the plan does lead to some messy situations in metropolitan areas,
which will be increasingly forced to adopt "overlay" codes. The result
will force these areas to include the area code in dialing local numbers
(i.e. ten-digit dialing), even to numbers in the same NPA, even across
a street.
The dynamics of today's growth in telephone numbering probably exceeded
the wildest expectations of yesterday's telephone planners. Now, there's
something of an NPA-of-the-Week club in effect.
Q: What "interchangeable" area codes been assigned?
A: The first known assignment was for Alabama: the existing area 205 was
be split up, with a new 334 area assigned effective January 1995.
Washington state's 206 area was subdivided to form the new 360 area
(Seattle, the major population centre, kept the 206 area code). Chicago
received a new 630 overlay area code, and Los Angeles a 562 area code.
Arizona's 602 area also split, forming the new 520 area in March 1995.
An NPA 456 was assigned for "inbound international" purposes, which will
not be an active area code within North America as such; 456 will be used
for calls from outside the NANP to select an international carrier for
certain calls into North America.
There are many new area code assignments, documented in Carl Moore's
history of area codes document. This is available from the TELECOM
Digest Archives. TELECOM Digest also carries postings announcing
new area codes as they become known. Bellcore's website at
http://www.bellcore.com/ also contains some information on announced
area code assignments.
Some documents regarding numbering plan issues have mentioned the
need to distinguish between area codes that are geographic (regular
telephone service within a given region) and non-geographic (800, 900,
or other service not necessarily confined to a specific region). It
appears the new non-geographic area codes are to end in double-digits
(such as the new 888 toll-free code; thus 233 would also be a
non-geographic code, as would the existing codes 500, 800, 900, etc.)
Another plan originally called for the use of the area code's middle
digit to determine whether an area code was geographic or not. Another
issue is future expansion of the area code system that will be required
if the NANP is to move beyond the current 3-digit NPA/7-digit number
format.
Q: What about expanding area/STD codes in other countries?
A: Many countries tend to use variable numbers of digits in the local
numbers and STD/area code numbers, thus there is often flexibility
in assigning new codes or expanding the capacity of codes. Sometimes
codes are changed to provide for extra capacity or to allow for
a uniform numbering plan such as ensuring the total number of digits
of the STD/area code plus the local number is constant within a
country.
In the UK, the digit '1' was added to most area codes as of 1995 in
order to create extra STD code capacity. For instance, London's 071 and
081 codes were changed to 0171 and 0181 respectively (internationally,
this change was +44 71 and +44 81 to +44 171 and +44 181).
France will change its system again, to divide the country into a few
regions of single-digit area codes. Presently, Paris has an area code 1,
with the remainder of France having no area code as such; eight-digit
local numbers are used in and out of Paris. The areas outside of Paris
would then get one-digit area codes corresponding to particular regions.
Australia is converting to single digit area codes, with uniform
eight-digit local numbers. This replaces the current system with
variable-length area codes and local numbers. This new plan is being
phased in throughout the 1990's. New Zealand also completed a change
to single-digit area codes, with uniform seven-digit local numbers.
Hong Kong actually got rid of its area codes a few years ago, replacing
the few single-digit area codes with seven-digit (and now eight-digit)
local numbers throughout Hong Kong. Then there's the anticipated
1997 takeover by China, which likely means another international dialing
change under China's country code.
Q: How are area codes assigned?
A: In many countries, an area code 1 (or 01) will be assigned to the
capital city, or most populous city. There are exceptions, such as
Mexico where Mexico City's area code is 5. Area codes of one or two
digits (excluding embedded access digits such as the 0 of 01, say)
will tend to be assigned to the largest cities, while area codes in
smaller centres tend to have more digits.
Some countries are modifying their numbering plans for various
reasons.. Sometimes this is done to increase numbering capacity (as
mentioned earlier). Sometimes this is done to create a more consistent
numbering plan so that telephone equipment can expect a predictable
number of digits in national telephone numbers.
A few nations use fixed-length area codes. Turkey recently established
a three-digit national area code system. New Zealand moved to single-
digit area codes, and Australia is in the midst of converting to a
single-digit area code system.
In country code 1 (U.S., Canada, much of the Caribbean) 212 and 213 were
assigned to New York and Los Angeles respectively, likely because these
area codes took the least amount of time to rotary-dial. A few other
metropolitan areas also had shorter rotary-dialing properties (312
Chicago, 313 Detroit). An area code like 907, on the other hand, took
longer to dial on a rotary phone. The original plan was to use a middle
digit of 0 where an area code covers an entire state or province, and
middle digit 1 in states or provinces that have two or more area codes;
this arrangement could not be maintained due to subsequent area code
requirements.
In the UK, an additional digit '1' was incorporated into the geographic
area codes (e.g. London's 071 STD code became 0171). Area codes may
still have varying numbers of digits, but the goal is to provide a fixed
total number of digits in the area/STD code plus local number.
Still, in other countries, this is not an issue if there are no area or
STD codes used. The initial digits of a local number will determine the
place or purpose of the number.
Q: What is Bellcore?
A: Bellcore, or Bell Communications Research, is a company that is jointly
owned by the seven Bell Regional Holding Companies. That is, Bellcore
assumed the duties of the Central Services organization in the old AT&T
following its court-ordered breakup (known as the AT&T Consent Decree
(Modified Final Judgment)). This was more commonly known as the
divestiture that established widespread long distance competition in
America.
Bellcore develops and sells technical documents relating to the operation
and use of the phone system, and does research and development on various
communications technologies. For instance, Bellcore was involved in the
MPEG video data compression method, designed to allow transmission of
entertainment-quality video.
Bellcore was actively involved in numbering plan issues, such as the
assignment of area codes and long distance carrier identification codes.
This activity, however, was to be transferred to a new North American
Numbering Plan Administrator.
Q: How can I contact Bellcore?
A: The Bellcore document hotline (with touch tone menu) can be reached at
1 800 521 CORE (i.e. 1 800 521 2673) within the USA and Canada, or
+1 908 699 5800 in other nations (+1 908 699 0936 is the fax number).
A catalogue of documents can be ordered through this number. General
information is also available on WWW (http://www.bellcore.com/).
For the voice menu on Bellcore's document hotline, to order a document
press 2 at the automated greeting. If you want to talk to a person
about availability, prices, etc, press 4 at the automated greeting.
Payment for documents can be made using American Express, Visa, Master
Card, International Money Orders, and Checks on US Banks. If you don't
have a document number handy, a catalog of technical documents is available.
Bellcore Technical Advisories (TAs) and other preliminary "advisories"
are only available by writing:
Bellcore
Document Registrar
445 South Street - Room 2J-125
P. O. Box 1910
Morristown, NJ USA 07962-1910
The mailing address for ordering other "standard" documents (including
Technical Reference ("TR") documents) is:
Bellcore Customer Service
60 New England Avenue
Piscataway, NJ USA 08854-4196
NPA/NXX (area codes, exchange codes) information is maintained by
the (somewhat) separate Traffic Routing Administration (TRA) group,
at +1 201 829 3071.
For all other TRA "products", or information about on-line access to a
database of routing data, contact the TRA Hotline at +1 201 829 3071,
or write to:
Traffic Routing Administration
Bell Communications Research, Inc.
435 South Street, Room 1J321
Morristown, NJ 07962-1961
If you want to talk to the "pub" folks, or a technical person, the
numbers/addresses are in the front of any TR (and the "Catalog").
Note that certain Bellcore documents (particularly certain TRA documents),
require the signing of a "Terms and Conditions" agreement before purchase.
Q: How can I get exchange/billing data? What is a V&H tape?
A: Bellcore sells the NPA-NXX Vertical and Horizontal Coordinates Tape
(the "V&H Tape"); this is primarily for billing purposes and lists
(for each NXX, or central office code) the type of NXX, major/minor
V&H coordinates (a sort of "latitude" and "longitude" used to calculate
rate distances for long distance billing), LATA Code (identifying the
U.S. long distance service area), the RAO (revenue accounting office),
Time Zone, Place Name, OCN (telephone company identifier) and indicators
for international dialing and "Non-Dialable".
Other related Bellcore documents include:
- NPA/NXX Activity Guide lists all NPA/NXX codes scheduled to be added,
removed or "modified" (monthly). There's also an Active Code List that
lists all NPA/NXX codes that aren't planned to be removed or "modified"
for the next 6 months.
- Local Exchange Routing Guide (LERG) contains information on all
USA/Caribbean destinations, switching entities, Rate Centers and
Localities, Tandem Homing information, operator service codes,
800/900 NXX assignments, etc. (three 1600 BPI tapes). Mostly useful
to interexchange carriers (IXCs) and other telephone companies.
- Telephone Area Code Directory (TACD) is a document listing area
codes according to location (ordered by state/province and place).
TACD also includes a list of Carrier Identification Codes (CICs)
used for 10XXX+ or 950.ZXXX long distance service selection.
In other nations, the first place to ask would be the telephone
company responsible for the local service, or the telecommunications
regulatory administration.
Q: How are letters dialed? What was "2L5D"? What is All Number Calling?
A: In the United States and Canada, local dialable numbers were
originally represented with an exchange name followed by numeric
digits. For example, "CEntral 4.5678", "GRover 7654" or
"PARkdale 1212".
Depending on the territory, the first two or three letters would be
used for the initial digits of a local call, generally highlighted
in capital letters. The above examples mean the numbers would be
dialed "CE4 5678", "GR 7654" and "PAR 1212".
Letters would represent digits on the North American dial as follows:
Letters Digit
======= =====
A B C 2
D E F 3
G H I 4
J K L 5
M N O 6
P R S 7
T U V 8
W X Y 9
Thus "CEntral 4.5678" is dialed as 234.5678. C in "CEntral" is for
digit 2, letter E is for digit 3. The "ntral" part of "CEntral"
was not for dialing, of course.
0 and 1 were not (officially) given letters since these could be
confused with the letters O and I, and these were used in special
services such as Operator (0) or early directory assistance or
faults reporting numbers (113, 114).
Q is not included in the North American dial, possibly because that
letter generally restricts the following letter to be U (Qatar or
Iraq are uncommon exceptions).
As for the letter Z, there are rare cases where Z was shown with 0
(perhaps representing "Zenith" reverse-charge numbers in some areas,
the forerunners of toll-free 800/888 numbers).
Some phone systems have set up the Q and Z letters on the 0 digit,
or perhaps the 1 digit, in order to provide certain features within
the phone system, or for use with applications where letters are
entered with the use of the keypad.
Other letter/number formats are available in some other countries
(often not using the North American standard). Some standards are
proposed or being implemented.
"2L5D" is short for 2 Letters, 5 Digits: the early standard-length
7-digit local numbers in the North American Numbering Plan.
Around the 1960s, All Number Calling began to replace the 2L5D format.
There were concerns that 2L5D had its limits since there were some number
combinations that were difficult to represent as names. 95 cannot be
realistically be expressed in names. There were limited possibilities for
a few other numbers such as 55 (KLondike, LLoydminster). The telephone
powers-that-be (basically AT&T) decided that telephone numbers were going
to be all-numeric. Thus "CEntral 4.5678" would be changed to "234.5678"
and the 2L5D era was phased out.
Bell Canada had a similar history with its telephone numbers.
All Number Calling was mostly in place there in the mid-1960s.
Letters in phone numbers have made a comeback, mainly for advertising
purposes. Toll-free numbers are often given as 1 800 <name> (or
1 888 <name>), even if the name represents more than 7 digits.
Any extra digits in those cases are ignored as surplus by the
telephone switches.
--------------------
Regulatory & Tariffs
--------------------
Q: How are long distance call costs rated?
A: This depends on the country or region, and even long distance carrier.
A common method of call rating depends on the "rate distance", a
calculated distance between the originating exchange and the destination
exchange. This is usually done on the basis of designated exchange
locations on each end of the conversation. The exact customer telephone
locations are not used as such a calculation would be too impractical
(too many locations to keep track of, for one thing).
Another form of rating depends on zones. Calls within a zone incur a
certain rate, while calls to other zones incur different rates. Some
long distance carriers may assess a constant rate per minute for all
domestic long distance calls, at certain times, regardless of where the
call originates and terminates.
Telephone directories of some nations may include a table that provides
all the ratings between points, depending on the area or STD codes
involved. Such ratings normally correspond with distance between the
main centres represented by the STD/area codes.
North America
Within North America, rate distance is calculated using the "V&H" system.
V stands for "vertical" (north-south position) and H for "horizontal"
(east-west position). Each exchange is represented by a location expressed
as a V&H co-ordinate. A rate distance can be calculated from two V&H
co-ordinate sets based on Pythagorean Theorem, i.e. rate distance =
sqrt((V1-V2)^2+(H1-H2)^2)/10 where (V1,H1) is the V&H for one end of a
call, and (V2,H2) represents the other end of a call.
The V&H system was based on the Donald Elliptical Projection, named after
Jay K. Donald of AT&T who created this method in 1956. The idea is to
"flatten" the Earth - a calculation based on a flat plane is easier than
doing the trigonometry on those degrees, minutes and seconds of latitude
and longitude. Two other references to this work include "V-H Coordinate
Rediscovered" by Eric K. Grimmelmann, Bell Labs Technical Memo, September
1980 and some notes by Jay Donald 17 January 1957. An internal Bellcore
memo on the subject by Ashok Ingle was also reported.
Conversion between latitude-longitude and V&H systems is possible. A C
program to determine V&H from latitude-longitude was posted in TELECOM
Digest V15 #362 (an episode that contains other useful discussion of
V&H). Other conversion programs are not widely known or are privately
created.
A program called NPA by "PC Consultant" in Houston provides V&H
information to map NPA-NXX (central office codes) with zip codes, place
names, etc. This is a shareware program that has been distributed via
Compuserve and possible via web or FTP sites; it should be available at
least in DOS and Windows versions. There may be other software packages
available with such features, however.
Other Nations
For other nations, rate calculations may be available in long distance
tariffs. Availability and accessibility of such tariffs will depend on
the countries and companies involved. Distance and time are the normal
factors of charging a call.
While North America most often bases its long distance charges for
each minute, or each 6 seconds for some services, some other countries
use a meter pulse - a set charge is incurred for each pulse. The more
costly the call, the more rapidly pulses occur.
Wireless/Cellular Call Rating
For wireless rating, the issues become more complex. In a cellular
system, one might expect an "airtime" component that depends on the time
used by a cellular phone as it communicates with a base station. This
could not depend on distance since current systems cannot pinpoint the
exact location of a cellular phone. For local and long distance, a
"landline" charge component, usually based on wireline call ratings,
would be added, depending on the base station through which a call takes
place. Exact information on wireless call rating can be obtained from the
companies involved (at least sometimes).
Q: What's this about the FCC starting a modem tax for those using
modems on phone lines?
A: Much of the "modem tax" talk of recent years has been of the tall urban
legend variety, on the order of the Craig Shergold story (yes, folks,
Craig's doing okay as of last report and he doesn't need cards of any
kind). It started when the FCC took up a proposal that, if it had passed,
would have raised the rate that certain modem users paid, notably those
who have set up their own long distance networks for public use, like
Compu$erve. The proposal was not enacted into law.
Local exchange companies levy "access charges" for use of the local
network by long distance carriers. "Enhanced service providers" (ESPs)
or services acting on the nature or content of customer provided
information, or which permit user interaction with stored information,
are exempt from such access charges and can obtain local service at
constant monthly usage insensitive rates (where available). The "modem
tax" would occur if the ESP exemption were to be removed.
Nevertheless, tales of rate increases and modem taxes could come up
again in the future. Here's how to tell the facts from the urban
legends. (1) Demand documentation; don't act until you see a copy of
the FCC proposal. (2) Once you have the proposal, look at the number.
It will be in the form yy-n, yy-nn, or yy-nnn. The first number, before
the hyphen, is the year. If, for example, it's the infamous 85-79, you
know it was the 79th proposal all the way back in 1985, and no longer
matters. (3) If you do see an up-to-date proposal, read it carefully.
If you can't tell what part of it enacts a "modem tax", demand that
the person who wants you to act explain it to you. If they can't, or
won't, then (and only then) bring it up on Telecom Digest, making sure
that you always include the FCC proposal's number, so that people know
which document you're talking about.
One report from Massacheusetts reports of proposals to charge state tax
on any user fees collected for bulletin boards or on-line services. (The
stated reference of state law is 830 CMR 64H.1.6 for those wanting to
confirm or deny this information). Those running no-charge BBSes should
not be required to charge tax on a zero cost, though.
Regulators in other countries may also have similar types of notices. The
CRTC in Canada issues public notices and decisions on telecommunications
using similar numbering schemes. Hoaxes such as fax/modem line surcharges
and imaginary BBS licencing threats have surfaced in recent months; all
of these have proven to be unsubstantiated.
Q: Why is a touch tone line more expensive than a rotary dial
line (in many places)?
A: This has been an occasional debate topic in the Digest. Indeed, there
can be a surcharge from $1 to $3 per month to have the ability to dial
using touch tone.
The tone surcharge is a holdover from the 1960's, when this technology
was introduced. Originally, decoders would be incorporated into crossbar
exchanges, or tone converters added to step-by-step switches. The tone
surcharge thus reflected the costs of the technology that was available
at the time. Today, cheap integrated circuits are readily available for
tone decoding and are a standard part of today's electronic switching
systems. Tone detection costs are thus negligible (and some would argue
tone detection saves costs), and in fact is easier for the phone company
to administer than the old pulse/rotary dialing methods.
Today's technology generally fails to warrant these tone surcharges.
The continued use of these surcharges, then, may be in order to allow
LECs to retain a revenue stream without appearing to increase rates for
basic local service. Regulators have allowed the process to continue.
Some have suggested tone dialing charges reflect the value of a demanded
service; tone is better, thus a premium is claimed for this perceived
privilege. Widespread acceptance of tone dialing today makes this appear
to be less of a luxury than in the past, however.
Some telephone companies have abandoned a premium charge for tone
dialing by including this in the regular local service charge. Others
may be phasing out the tone surcharge and adjusting local rates to
reflect conversion of all customers to tone dialing. Others still
collect some form of tone surcharge.
Q: How come I got charged at a hotel for a call where no one answered?
Why is the timing on some of the long distance carriers inaccurate?
A: Where actual call supervision is unavailable or inconvenient, some call
billing systems will guess when a call might be answered. That is, a
customer dials the call, and the equipment times the progress; after a
certain point in time the billing will commence whether or not the party
at the other end actually answers the phone. Thus, calls left ringing for
more than five or six rings can be billed. Adding to the problem is the
fact that calls don't necessarily start ringing at a fixed time after the
last digit is dialed.
Needless to say, some calls can be left uncharged in this scheme. Should
the call be answered and completed before the billing timer elapses,
the call won't be billed.
There are reports that California requires proper billing and supervision
of calls. Other areas may adopt similar requirements. Technological
advances, consumer demand and regulation changes should make the stories
of inaccurate call billings a thing of the past.
Q: What is AT&T Tariff 12?
A: The long distance carrier AT&T uses a "Tariff 12" pricing to set up a
special deal with specific companies. These tariffs are set up so that
the company for which the deal is made is not named, but its
telecommunications situation is described in detail. This means that any
other company that has a similar situation is also entitled to the same
custom provisions.
Tariff 12 deals are the subject of occasional scorn from competing
carriers. The non-AT&T companies do have freedom to offer custom deals
of their own, however. AT&T still has the majority of the long distance
market, and the after-effects of the former monopoly service linger.
Concerns remain regarding AT&T's apparent market dominance, prompting
continued regulatory checks and balances for now.
Q: What are the ITU and CCITT?
A: ITU is the International Telecommunication Union, the Geneva-based
United Nations agency dealing with international telecommunications
standards.
CCITT (the French acronym for the International Telegraph and Telephone
Consultative Committee) is the former telecommunications standards body of
the ITU. CCITT is now known as the ITU Telecommunication Standardization
Sector (ITU-T) effective 1 March 1993.
Other former ITU divisions (prior to the 1993 changes) besides CCITT
included the General Secretariat, the International Frequency Registration
Board (IFRB), the International Radio Consultative Committee (CCIR),
and the Telecommunications Development Bureau (BDT). (Note that some
of the abbreviations in ITU correspond to the French language names).
The new ITU organisational structure includes the Radiocommunication
Sector (ITU-R) and the Telecommunication Development Sector (ITU-D)
as well as the previously-mentioned Telecommunication Standardization
Sector (ITU-T). ITU-T includes the standards making activities of the
former CCITT and CCIR. The former BDT's activities now fall under the
ITU-D jurisdiction.
The World Telecommunication Standardization Conference (WTSC) (formerly
CCITT Plenary Assembly) makes the decisions regarding international
telecommunications standards. Standards for such things as international
directory assistance handling, country code numbering, and other
technical matters are decided by the WTSC. The former CCITT Plenary
Assembly published volumes of these standards every four years, with
each session's volumes identified by a colour. The 1988 Blue Books were
the last ones to be published from a Plenary Assembly, after which a
decision was taken not to continue the publication of standards in this
format. Recommendations are available separately, and updated as needed.
Standards are referred to as Recommendations such as ITU-T Recommendation
X.400 regarding electronic mail, or E.164 regarding international
telecommunications numbering. (These were formerly referred to as
CCITT Recommendations; anything that was a CCITT Recommendation
automatically became an ITU-T Recommendation).
ITU's Telecommunication Standardization Bureau (TSB) replaces the
function of the former CCITT Specialized Secretariat.
-----------
Competition
-----------
Q: Which countries have competitive telecommunications services?
A: Originally, local and long distance telephone services were provided
by a monopoly whether this was under private or government ownership.
Today, deregulation of telephone companies and telecommunications is a
worldwide trend. For better or worse, the international marketplace is
demanding more innovation and competition in telecom markets in such
areas as electronic mail, fax and data services as well as the long
distance, local, satellite and other network services.
Australia:
Optus was the first long distance competitor effective 1992. It is
licensed to compete with Telstra (the former monopoly) in local,
national, international and mobile services (although not much local
competing service is reported yet). Vodafone is another competitor in
the mobile market.
Canada:
Canada permitted public long distance competition in June 1992. Prior to
that, there was limited competition in terms of such things as fax
communication services and various long distance/local service resellers,
aimed at business interests. Unitel (now known as AT&T Canada) and
BCRL/Call-Net (now known as Sprint Canada) were successful in their
application to compete. A subsequent appeal of certain aspects of this
decision was made by Bell Canada and other existing telephone companies.
The decision withstood this appeal, finally permitting full-scale long
distance competition.
Local service competition was declared open by the Canadian regulator
(CRTC) late in 1994. No significant plans have yet been announced for
the provision of new local services, other than some cable company
Internet access services. Some specialty business services are also
available. There was at least one university student residential local
service established, competing with Bell (at York University in Toronto).
The local competition framework and rules are to be formalised by the
CRTC.
Chile:
Chile has a highly competitive telephony market. There are nearly
10 local providers and nearly the same number of carrier companies.
Each carrier company can be accessed by any subscriber of the country
by dialing a three digit 1XX code. Major carrier providers are
Entel (37%), CTC Mundo (31%), Chilesat (21%).
The Chilean market is pushing new access technologies such as FRA and
telephony over cable TV. The main reason for this is that, even if
there are a lot of companies on the local market, CTC is still holding
95% of it.
Europe:
There is a directive within the European Union that member nations are
to allow a certain level of communications competition by 1998. Long
distance competition, at least, will eventually be established in
those member nations.
International and mobile communications in France have long been
open to competition, although the local and long distance services
are still only available as a monopoly service for now.
Finland:
Competition in the Finnish telecommunications market is largely a duopoly
between Telecom Finland (the former PTT/Tele) and Finnet, a consortium
of the about 45 regional telecoms. Telivo, a daughter company of the
power company IVO has started operations in long distance and international
access, and plans to go ahead with a DCS1800 digital cellular system as
will both of its competitors.
PTT monopoly in business fax/data long distance was ended in late 1980's,
in mobile phone market in 1991, in long distance calls on 1 Jan 1994, and
in international access on 1 Jul 1994. Local network access still is a
virtual monopoly of each regional company, with limited competition using
dual local networks, and partly with short range cellular handsets.
Israel:
Israel will start offering during 1997 competitive carrier services,
with two additional providers: Barak and Golden Channels, to share the
market. Bezeq thus loses its monopoly.
Telrad Telecommunication Industries is an Israeli based hi-tech
factory with approximately 3000 workers, working in a strategic
alliance with Nortel (which currently owns 20% of the company).
Telrad has involvement in the Chile market as well as in Israel.
Japan:
Domestic long distance competition since the mid/late 1980's consists
of NTT (Nippon Telephone and Telegraph, the former national monopoly),
Japan Telecom and Teleway Japan and DDI. A triopoly exists for
international services: KDD (former international monopoly), IDC and
ITJ. NTT operates most local service.
Mexico:
Mexico reportedly is opening competition in long distance services
by the late 1990s.
New Zealand:
New Zealand now allows free entry into telecommunications. Any party
wishing to establish a network may apply to be a registered network
operator. Clear Communications is one notable New Zealand long distance
competitor.
United States:
Competition in long distance services began in the early 1980s with the
court-ordered dissolution of the Bell System into such pieces as regional
local telephone providers, AT&T (long distance) and Bellcore (research,
administration of telephone standards, etc.). Today's choice of carriers
include: AT&T, MCI, Sprint, LDDS (which bought Metromedia/ITT and ATC,
and more recently WilTel), Cable & Wireless, and Allnet.
Competing local network plans were recently established. Companies such
as networkMCI and cable companies are expected to provide alternative
local services in a growing number of markets.
United Kingdom:
The UK had a duopoly long distance situation: British Telecom and Mercury
provided long distance services. Effective with a 1991 UK Government White
Paper, more carriers were allowed to provide local and long distance
services. These include Energis, Ionica, ACC, WorldCom, City of London
Telecommunications, MFS (UK), Millicom and others. BT and Mercury hold
the only licenses to provide facilities based international service using
undersea cables, although most resale is virtually unregulated.
International satellite services not interconnected into the switched
network may also be provided by virtually any party.
Other nations:
Hong Kong is in the process of offering local licences to compete with
Hong Kong Telecom (due to start 1 July 1995).
India called for bidders for local licences to compete with the
Department of Telecommunications (DoT) on 16 January 1995.
Many Asian nations are expected to develop telecom competition: Korea,
Vietnam and Singapore are nations to watch. China may develop a
competition between two government monopolies, if certain reports
are correct.
Q: What is a COCOT?
A: Customer-Owned Coin-Operated Telephone, or perhaps Coin-Operated
Customer-Owned Telephone. Essentially, this is a privately-owned public
telephone as opposed to the traditional payphone that is owned and
operated by the local telephone company. Most COCOTs exist in the United
States; their status is not too well-known outside the U.S. Certainly
there are no approved COCOTs in Canada as such and they are also likely
rare or nonexistent in other nations.
The COCOT is the target of much scorn as it often delivers less than what
one would hope for in competition. Cited deficiencies of many of these
units include prohibiting access to carriers like AT&T, use of default
"carriers" that charge exorbitant rates for long distance calls, etc.
Some of them have had problems when newly activated area codes were used.
In some cases, COCOTs would not even place calls to numbers whose new
area codes could not be dialed and whose old area codes could no longer
be dialed.
Q: What is an AOS?
A: AOS is short for Alternate Operator Service. That is a company other
than a long distance carrier or local telephone company that provides
operator assisted services for long distance (collect, third number
billed calls, person-to-person, etc.). Normally this involves having
operator staff handle billing and the necessary dialing, but the AOS
companies make use of existing long distance services rather than have
their own network. Using an AOS, whether for a collect call or credit
card call, can be more expensive than bargained for.
Often, COCOTs (see above) will have their default "carrier" set to
an AOS, for optimum revenues. Hotels may also set up phones to use
AOS services by default.
Q: What is "splashing"?
A: Suppose you place a call from city A to city B using an AOS based in
city C. The call is considered to be "splashed" if the billing for the
call is based on the distance between city C (AOS) and city B
(destination) rather than between cities A and B as one traditionally
expects such calls to be billed. Thus, if the splashed distance (C-B)
is much longer than the origin-destination (A-B) distance, the customer
may be charged extra money. Of course, if the AOS city is close to the
called party's location, the charges could be less than what might be
normally expected. In any case, splashing causes a distortion of the
normal long distance rates.
Splashing in the United States is illegal according to the federal
Telephone Operator Consumer Service Improvement Act.
Q: Where can I find a list of equal access (10XXX) codes?
A: The TELECOM Digest Archives has lists of these codes. They are contained
in the files occ.10xxx.access.codes and occ.10xxx.list.updated in the
TELECOM Digest Archives. New information on these codes or other access
codes occasionally appears in TELECOM Digest.
A Carrier Identification Code (CIC) is the XXX portion of a 10XXX code
that identifies the long distance carrier in the United States and
Canada. The 950.XXXX carrier access numbers also incorporate the CIC.
That is, 10999 and 950.0999 would represent the same carrier.
Note that 10XXX codes are becoming (or will soon become) 101XXXX codes
to allow for more carrier assignments. This format will be phased in
over the next few years, allowing both old and new codes to be used
temporarily. The 101XXXX format may already be active in certain areas.
The FCC issues these Carrier Identification Codes (CICs) and as such would
maintain an official list of these. Bellcore also offered publications
that contain CIC lists; one such list was included in the Telephone Area
Code Directory (TACD) publication. (see "How can I contact Bellcore?"
question for details on purchasing Bellcore documents).
In Canada, a list of CICs used by Canadian carriers is maintained by
the Canadian Numbering Administrator, part of the Industry Canada
government department. These are co-ordinated with the U.S. CICs and
thus should not conflict with U.S. assignments (although there are
a few companies that have CICs assigned for use in both Canada and
America).
Q: How can I tell who my default carrier is (or which carrier belongs
to a 10XXX+ code)?
A: In most areas of the U.S. and Canada, dial 1 700 555.4141 to get a
recording indicating the default carrier. This should be a free call.
From regular lines, dialing 10XXX (or 101XXXX) + 1 700 555.4141 should
yield the identifying recordings of other carriers in most cases. Note
that some carriers are not available in all regions, and that some
carriers do not set up a recorded identification message.
There are reports of telephone lines in the U.S. that are set up without
a default carrier. Each long distance call thus requires the selection
of a specific carrier with a 10XXX or 101XXXX code.
Default carrier identification in other nations was not available
for this FAQ. This depends on how each nation sets up the numbering
plan to accomodate competing carriers, and whether a default carrier
system is established.
On U.S. payphones, AT&T is normally a "default" carrier for coin calls,
but not necessarily so when it comes to calling/billing card numbers,
collect calls or other operator-assisted calls. This explains instances
where AT&T's recording is heard regardless of what carrier access codes
are used before 1 700 555.4141.
There can be exceptions to the AT&T only rule, such as the arrangement
of New Jersey Bell, which is not only a local telco but also a regional
long distance carrier. Their 10652 (or 10NJB) equal access code can
be used at payphones, and for inter-LATA calls from certain New Jersey
points to New York City and Philadelphia.
COCOTs often handle coin calls with self-contained coin billing
equipment (and guessing the call connection time, unless there should
actually be some call supervision or billing arrangement with the
local telco).
No information was available from other countries as to how a
default carrier would be identified, where a competitive carrier
situation exists.
Q: What is a LATA?
A: LATA means Local Access Transport Area. This is a geographical area
defined in the United States to determine whether the local telephone
company handles long distance traffic, or whether this must be routed
to an inter-exchange carrier such as MCI, Sprint, AT&T, etc. Some LATAs
consist of an entire state, others consist of a part of a state (and
sometimes a few exchanges in adjacent states).
Recently, competing carriers have been permitted in some areas to handle
long distance calls within the same LATA. The trend towards intra-LATA
competition is bound to continue as technology and regulation permit.
In Canada, there was no concept of LATA when full-scale long distance
competition was introduced in 1992. That means competing carriers
or local telephone companies can handle and bill long distance calls
regardless of call origins and destinations.
Q: Where can LATA maps be found?
A: The BOC Notes on the Intra-LATA Networks publication by Bellcore
(at least the 1986 version) had some state maps outlining the various
LATAs and their boundaries.
Some phone books indicate which exchanges are in a LATA, sometimes
with a map that indicates the boundaries of LATAs within a state.
CCMI (Center for Communications Management Information) also sells
LATA maps. (CCMI can be contacted at 800 929.4824).
McGraw Hill's business publishing division reportedly printed a LATA map.
--------
Features
--------
Q: What is the calling card "boing" and what is it made of?
A: When a North American call is dialed as 0 + area code + number, a
"boing" is heard after the number is dialed. This is the prompt to
enter a telephone company calling card number to bill the call with,
or to select the operator (0) for further handling, or in some regions
to specify collect or third number billing for the call.
The boing consists of a very short burst of the '#' touch tone, followed
by a rapidly decaying dial tone. The initial '#' tone is used in case
certain tone-pulse converters exist on the line; such converters use the
'#' to disable conversion of tones to dial pulses, a conversion which
would prevent card number entries from reaching the long distance provider.
Q: What are codes like *70?
A: Such codes are used to activate and deactivate telephone features
(eg. Call Waiting or Speed Calling). The format of these codes in
North America is *xx (where xx represents two digits), which soon
may be expanded to *xxx (three digits after *).
In the UK and other nations, the codes may look like #43* or *55*, for
example. Even within North America, there have been regional variations
such as 72# (or on a pulse/rotary phone, dial 72 then wait).
Since these feature codes vary from nation to nation (and sometimes vary
within a nation), a comprehensive list is not provided in the FAQ at this
time. Check local telephone directories or telephone company offices for
information on the codes used in a specific area.
The North American *xx codes were referred to as "Vertical Service
Codes" in at least one Bellcore document.
Q: How can one dial *70 on a non-touch-tone (pulse/rotary) phone?
A: In North America at least, 1170 can be used in place of *70.
Generally, use 11 on rotary/pulse phones to replace the * when
using special feature codes.
Q: How can I prevent the call waiting tone from beeping in
mid-conversation?
A: If you place the call, and don't want to get interrupted, a call
waiting suppression code is dialed before dialing the call itself.
The most common code for this in North America is *70 or 1170 (on
rotary dial phone lines). 70# (or 70 and wait on rotary phone) could
also be used in some areas. Other countries will have special codes
for this (like #43# in the UK), and will vary in terms of capabilities
offered.
Local phone companies in some areas charge installation and monthly
fees for 'Cancel Call Waiting', and you must subscribe for this to
work. In some areas it comes free with Call Waiting. In a few other
areas it may be unavailable at any price.
Thus, to call 555.0000 so that call waiting is disabled, dial *70
(or whatever the correct code is for your area), wait for another
dial tone, then dial 555.0000 as usual.
Suppressing call waiting tone on an *incoming* call may be possible
depending on how your phone company has set the central office.
One way of doing this is would be to flash your switch-hook briefly,
check for a dial tone, then try dialing the call waiting suppress
code (*70 or whatever). Southwestern Bell, for instance, uses a
variant of this: <flash hook> *70 <flash hook> (i.e. a second hook
flash required). The methods are not guaranteed, however; your phone
company might be able to give a better answer if the preceding
doesn't work.
NOTE: each phone company will determine the capabilities of Call Waiting
features, and what codes will be used to activate them, and what costs
the service will be provided at. The codes are not necessarily the same
from place to place. Please consult your phone company for official
information in your particular area if any of the above codes do not work
properly. Also check the phone book introductory pages as these sometimes
include instructions on how to use special calling services such as
Call Waiting.
Q: What is distinctive ringing?
A: First, distinctive ringing is a feature that offers extra numbers
which cause different ringing patterns on a line. When the main number
is called, the called party will receive the normal ringing pattern.
If one of the extra numbers is dialed, that line would ring with a
different cadence. In North America, the normal ringing pattern is
a single ring every six seconds. The distinctive ring patterns are
1) two short rings every six seconds, or 2) a short-long-short ring.
Different ringing patterns are also used in conjunction with such
features as busy call return, to indicate a freed line. One test
done by Bell Canada set up a special ringing pattern (different from
any of the featured distinctive rings) to indicate an incoming
long distance call.
Each telephone company has its own name for this feature: Ident-a-Call,
Teen Ring, Feature Ring, etc. In any case, different ringing patterns
allow for calls to certain people, or to sort out different call
purposes such as for voice, fax, modem, or answering machine.
Numerous companies offer devices that detect distinctive ring patterns
and route calls to distinctive lines. Distinctive ring detection is
now a common feature of fax machines. Electronics shops, computer
stores, telecom shops, business supply shops, etc. are good places to
look for these devices. There are also some mail-order companies that
specialise in telecom or electronic products. No doubt some sources
can be found on the WWW.
Costs for ring detection devices vary, but should not be more than
USD $80 to 100, and with the usual progress of technology, should
likely cost less.
The March 1994 edition of Electronics Now magazine had a distinctive
ring detector project, for those who wish to do it themselves. This
project may need substantial modifications for use outside the U.S.
and Canada, if customer-built attachments are permitted at all.
-------------
Miscellaneous
-------------
Q: Is there a way to find someone given just a phone number?
A: Sometimes. There are often cross-referenced city indexes available in
libraries and other places that have lists ordered by the phone number.
These directories go by names such as Bowers, Mights, Strongs or other
brands. One catch is that such directories are necessarily out of date
shortly after their publication what with the "churn" of changing
telephone numbers and addresses. Still, these are at least annually
updated, and are available at a price from the directory companies
involved.
In addition, there are phone numbers provided by telephone companies
that connect to live lookup services. Operators at these numbers will
determine a person according to the phone number. Only a few of these
lookup numbers are intended for the general public (e.g. Chicago and
Tampa). Some countries have also provided number to name lookup as a
matter of normal telephone service, although these are often chargeable
calls. Otherwise, most of these lookup numbers are for internal telephone
company usage. Again, unlisted numbers are not intended to be provided
by these services, while the listed numbers are often found in the
introductory pages of local phone books.
The Compuserve on line service had a facility (Phone File) to find
names and addresses based on phone numbers. This facility is supposed
to have more recent information for residential numbers than for
business numbers. There are some concerns that the Phone File is not
as accurate as it should be. Those interested should contact Compuserve
staff for assistance or information on this service.
Extra-charge numbers have been set up to provide reverse-directory
services. Note that in some cases charges may apply even for
unsuccessful searches:
* UnDirectory is an automated, touch-tone-operated service within the
U.S. (1 900 933.3330, $1 per minute, listing U.S. numbers)
* Telename (sp?) is a live operator "900" service available within the
U.S. during "business hours" (1 900 884.1212, give operator number,
await lookup; $1.49 first minute, $0.75 per additional minute).
* Chicago number lookups are available (312, 630, 708 areas) via
(312) 796.9600 (enter number on touch-tone; $0.35 for two lookups,
long-distance charge only outside Chicago). This service is operated
by Ameritech, the local exchange carrier in Chicago, thus this facility
tends to have high accuracy.
* In Canada, 1 + area code + 555.1313 has been established in some
areas as a "Name That Number" service.
* There may be similar numbers in other regions that offer such lookup.
If available, these would be listed in local directories.
CD-ROM phone directories have been produced and are now available most
places where software is sold. One of the more prominent producers of
these is Pro CD, Inc, of Danvers, MA USA, makers of the SelectPhone and
Canada Phone products. As such products are often typed in from annual
telephone directories, the information in these CDs is subject to change
or error.
Telephone companies have Customer Name and Address (CNA) offices which
provide number lookups. These are not intended for general public use.
Unlisted numbers are not listed, nor are they intended to be traced by
the general public.
Private detectives seem to have other means of getting these numbers,
but that's another story...
Q: Who are the Telephone Pioneers?
A: The Telephone Pioneers of America began almost a century ago, originally
consisting of the 'charter employees' of the company, or 'pioneers' in
telecommunications, mainly those who served with the Bell System at its
outset. As time went on, there would be fewer living or active original
Pioneers, thus the TPA charter was amended to allow membership by any
employee of AT&T or (as they were called) a subsidiary company who had
been employed by Bell (or an independent) for at least twenty years.
Membership in the Pioneers was opened to more types of telephone company
people over the years (including companies that are not "Bell" or AT&T).
The Telephone Pioneers have a distinguished history of community service.
Pioneers devise technical solutions to improve the lives of those with
disabilities, allowing them to use telephones when this would otherwise
be difficult or impossible. Pioneers also assist with general community
activities such as voter registration, help those who are ill, feed those
who are needy, and more.
The Telephone Pioneers of America has chapters throughout the USA and
Canada. At the non-Bell telcos, the same organisation is known as the
Independent Pioneers.
Q: Where can a Cellular/Mobile Radio mailing list be contacted?
A: A mailing list dedicated to cellular/mobile radio technologies, namely
new digital radio services, is available. Contact [email protected].
Fidonet has a CELLULAR conference for cellular telephony issues, for
those with access to that network.
The subject may appear in other Usenet newsgroups such as
comp.dcom.telecom.tech.
Q: How are VCR+ codes generated?
A: This is not a telecom topic, considering that the VCR+ is a device
used to program VCR machines for television viewing purposes. However,
the makers of VCR+ operate a 900 chargeable phone line within the
United States to allow citizens to obtain VCR+ coding information.
The VCR+ coding is a 1 to 8 digit number that represents the channel,
date, time and duration of a television program. These codes are
found in many television listings and appear to have no relation
with the time and channel that is represented.
This coding method was intended to be rather secret and inscrutable,
but this only served as a challenge to cryptologists. The coding
system was cracked for up to 6 digit VCR+ codes; the details on
the decoding were published in the journal Cryptologia some years
ago. Programs are also available via FTP sites for VCR+ encoding
and decoding at least a limited extent of these codes.
This topic is more appropriate for a newsgroup that deals with video
or television.
Q: What is CLLI?
A: Common Language Location ID (CLLI) is a method of identifying locations
and equipment. Bellcore developed the codings to allow the labelling
of buildings, exchange offices, facilities (even poles, shacks, etc).
Each full CLLI is eleven characters in length. Generally, the first
four characters represent the place name such as a town or facility.
The following two characters represents a state, province or other
territory. The remaining characters identify the particular item
within the place. In the case of switching equipment, these final
characters might be formatted as two characters for the central
office location, followed by other characters to identify the switch
type, and machine within the building.
A fictitious example, for Hill's Green, Ontario (HILL for town, ON
for province/state code), with a telco building in Bean Sprout (BS)
operating a remote switch (RS) could have a CLLI of HILLONBSRS0.
Q: Why do movies often use 555-xxxx numbers? What does 555 represent?
A: The use of a number that exists for an actual service can cause problems
if listed in a movie or broadcast program. Audiences will attempt to dial
the number out of curiosity.
In the United States and Canada, 555.1212 is the standard number for
long distance directory assistance calls. 555 was reserved in each
area code for that purpose and was generally only used for directory
assistance or perhaps special telephone company uses such as a business
office access.
In recent years, 555.xxxx numbers were made available for use by
businesses and telephone companies for special services. e.g. 555.1313
is used in many parts of Canada for a service that retrieves the
subscriber name based on a given phone number. 555 numbers in toll-free
(800, 888) and extra-charge (900) services were also made available.
A limited series of 555 numbers was protected by Bellcore (the numbering
administrator) for entertainment uses.
The choice of 555 probably reflected the quirks of the original "2L5D"
format i.e. local numbers were originally listed as two letters followed
by five numerics. The letters corresponded to dial digits - J, K or L
would represent the digit 5, for example. Since there were few names
that could be made from 55x numbers (KLondike and LLoydminster),
55x was deemed to be better used for special services rather than the
conventional phone service.
555 numbers could represent valid service numbers outside North
America, for areas having 7-digit local number formats. In Finland,
555-xxxx numbers are in use at least in both Finnish GSM networks.
Q: Are there cases of local calls across international borders?
A: Yes, mainly between Canada and the United States. There are several
points along the New Brunswick (Canada) and Maine (U.S.) border that
have cross-border local calling privileges. The known examples of
Canada-U.S. border local calls are:
Canadian side American side
--------------------------- ------------------------------
Clair, New Brunswick and Fort Kent and St Francis Maine
Edmunston, New Brunswick and Madawaska, Maine
McAdam, New Brunswick and Vanceboro, Maine
St Leonard, New Brunswick and Van Buren, Maine
St Stephen, New Brunswick and Calais, Maine
St Regis, Quebec and Fort Covington, New York
Rainy River, Ontario and Baudette, Minnesota
Coutts, Alberta and Sweetgrass, Montana
Point Roberts in Washington state used to have local calling access to
the Vancouver, British Columbia region on the Canadian side until that
connection mysteriously disappeared and calls between those areas became
long distance.
No known U.S.-Mexico local calling arrangements exist.
In other nations, "local" calling is often on a measured billing.
Still, cross-border local or special-rate calling arrangements could
theoretically occur.
Technically, calls between the Vatican City and Rome could be
considered a case of international local calling.
On Northern Ireland (UK)/Ireland (courtesy Paul Dundas):
"Some calls may be made from the UK to the Republic of Ireland at
local rates: parts of Northern Ireland which are close to the border
of the Republic may call numbers in the Republic on exchanges close
to the border, at local rates. This applies to payphones and domestic
and business lines. I believe that the same is true in the reverse
direction."
"In fact, even calls from Northern Ireland (BT) to the further flung
parts of the Republic of Ireland are not charged at the international
call rates, but at normal long-distance rates."
Q: Which countries have freephone or "800" services?
A: The "800" toll-free service in the United States and Canada is probably
the first automatic freephone service. The service has become so popular
that a new "888" code was placed into service to provide capacity for
more toll-free numbers. Previously, operator-handled services such as
"Zenith" or "Enterprise" (or collect calling) were used to call
companies at no charge to the caller.
The UK uses 0800 (British Telecom) or 0500 (Mercury) for toll-free
services. A 0345 code is used to complete calls at a local call rate.
Switzerland uses numbers beginning with 155 for its freephone services.
Numbers are of the form 155 xxxx. Outside Switzerland, these numbers
can be reached (at international rates, NOT toll-free) by using
+41 46 05xxxx (that is, area code 46, followed by 05 then the last
four digits of the 155 number).
Work is proceeding to establish an international "freephone" system
using international dialing. 800 was recently established as a toll
free country code to indicate the international freephone numbers.
Introduction of the service may occur in 1997.
Q: What is 'area code' 710?
A: In the North American Numbering Plan, 710 is listed as a code for
special government services. Specifically, it is used by the American
National Security and Emergency Preparedness (NS/EP) department.
There has been a level of secrecy presumed regarding the 710 service.
However, it has been found that the Government Emergency Telephone
Service (GETS) under the National Communications System (NCS) operates
a special telephone service that allows for priority-routed calls
that can be used by government departments such as emergency services.
Information can be found on the NCS/GETS website:
http://164.117.147.223/~nc-pp/html/new-gets.htm
One known 710 number is (710) NCS-GETS (627.4387) which connects to a
passcoded service. Those who are authorised to use GETS would enter a
passcode or PIN then proceed to place a call through that network. Note
that it should be stressed that this is not intended as a general
public service, but that this is a facility for special government
or emergency uses.
The idea is that the network will be resistant to network outages
and allow for communications in emergencies. According to the GETS
webpage, GETS does not interfere with public telecom traffic, nor does
it use a precedence-level facility like Autovon had.
A few elements in that TELECOM Digest discussion indicate that 710
might have been activated in the mid-80s. "Inets" was one reported
original name for the system.
TELECOM Digest had some discussion on 710 (see Vol. 16 #66, #69, #114).
Information was also reported in documents the Bellcore/ATIS sponsored
Network Operations Forum (NOF). NCS/GETS is public knowledge, but some
might suspect there are other secrets lurking in the phone system.
Q: How can one call freephone numbers from other countries?
A: Domestic toll-free services are intended for use within nations rather
than for access from international points. However, many countries have
set up agreements that allow for their domestic toll-free numbers to
route calls to subscribers in other nations. Thus a UK 0800 number could
reach a point in the U.S. or Canada. Such arrangements are normally
reciprocal, thus North American 800/888 numbers can also be arranged to
reach UK points.
Recent reports from the UK indicate that North American 800/888 numbers
can also be reached with the use of international dialing. These calls
are NOT toll-free but are charged at international rates, as if the
call were placed to a conventional North American number. The purpose of
this arrangement is to allow access to North American 800 and 888 numbers.
AT&T's USA Direct Service allows calls to North American 800/888 numbers
from other countries, providing USA Direct service is available. The
restriction that only AT&T's 800/888 numbers could be reached is no
longer in effect. However, the 800/888 number must be reachable from the
U.S. city at which the USA Direct call is handled. An AT&T Calling Card
is also required, and there will be international charges to reach the
U.S. from other nations.
Other home direct services may allow for the possibility of freephone
number access. Individual carriers will determine whether such service
is available and at what cost.
Some Canadian long distance carriers have a feature that allows calls
to U.S. 800 and 888 numbers that are not otherwise reachable from
Canadian networks. Charges for such freephone "bypass" are often
CAD$0.18 per minute (at one time, some carriers charged CAD$0.10).
Bellcore assigned 880 and 881 as codes for the purpose of reaching
North American 800 and 888 numbers on a "sent-paid" basis, or where the
caller pays to call an otherwise unreachable toll-free number.
The International Freephone Service (IFS) being set up (country code
800) will provide a convenient method of toll-free access via the
international dialing system. This may replace the use and call
forwarding of separate domestic toll-free numbers over time.
Q: Which World-Wide Web (WWW) sites have telecom information?
A: There are plenty of telecom-related web sites available, especially
in the past year or two. More of these will be announced in TELECOM
Digest (comp.dcom.telecom) as they are made available.
One could check index sites such as Yahoo (http://www.yahoo.com),
Lycos or AltaVista for telecom-related listings. Telecom companies,
equipment manufacturers, regulatory agencies and more are accessible.
Such listings are updated over time.
Note that any addresses listed here are subject to change. Those
listed are definitely not the only ones available; there should
be enough listed here as starting points in the grand tradition
of net surfing.
One major index of telecom-related websites is at:
http://www.spp.umich.edu/telecom/
Government/Regulatory/Standards bodies:
http://www.itu.ch/ ITU (int'l standards)
http://www.fcc.gov/ FCC (USA regulator)
http://www.crtc.gc.ca/ CRTC (Canadian regulator)
http://www.open.gov.uk/oftel/oftelhm.htm OFTEL (UK regulator)
National Companies/Consortiums:
http://www.inmarsat..org/ Inmarsat (satellite)
http://www.stentor.ca/ Stentor (Canadian telcos)
http://www.ntt.jp/ NTT (Japan)
http://www.singtel.com/ Singapore Telecom
http://www.telkom.co.za/ Telkom (South Africa)
http://www.vptt.ch/ PTT (Switzerland)
http://www.bt.net/ BT (UK)
Other Pages (personal or otherwise off the beaten path):
http://www.angustel.ca/ Angus (Telecom Update)
http://www.castle.net/~kobrien/telecom.html another telecom page
http://www.geocities.com/CapeCanaveral/8818 assorted items
Q: What's an ObTelecom?
A: ObTelecom, or Obligatory Telecom Content, is used whenever a Digest
article appears to be off-topic. But the ObTelecom banner assures
everyone that it really has *something* to do with telecom after
all. Or so one should think.
Q: Who contributed to this FAQ?
A: The initial edition of the FAQ was dated 28 August 1991.
Thanks to Nathan Glasser, Dan Boehlke and Maurice E. DeVidts and those
other inquiring TELECOM Digest minds for their frequent questions in
the early versions.
For v.3, the following people contributed comments, extra questions
and other updated information:
Alan Barclay, Steve Beaty, Rick Broadhead, Gordon L. Burditt, Tad Cook,
David G. Cantor, Tony Harminc, Carl Moore, Gary Morris, Dan Sahlin.
For v.4 the following people contributed more comments and information
(sometimes adapted from the regular Digest postings):
Mark Brader, Richard D G Cox, Brad Hicks, Dave Levenson, Don McKillican,
Jim Morton, Colum Mylod, Peter Sint, Pat Turner and Al Varney
For v.5 (1994) the following people are the source of even more
comments and information whether direct or indirect:
Jack Decker, J. Delancy, Adam M Gaffin, Fred R. Goldstein, Rich Greenberg,
Emilio Grimaldo, J. Brad Hicks, Chris Labatt-Simon, Fernando A. Lagrana
Andy La Varre, Marty Lawlor, Greg Monti, Carl Moore, John Paul Morrison,
Hans Mulder, Lars Poulsen, Paul Renault, Robert Shaw, Andy Sherman,
Bill Sohl, Bruce Sullivan, A Alan Toscano, Pat Turner KB4GRZ, vantek,
Victor R. Volkman.
For v.6 (1995) the following people are the source of still even more
comments and information whether direct or indirect:
Nigel Allen, Marc Baime Michael Bloch, Tad Cook, Jim Gottlieb,
Kimmo Ketolainen, Jonathan, Wes Leatherock, Carl Moore,
Blake R Patterson, Jonathan Prince, Anthony Sylvester, Eric Tholome,
Charles A. Tievsky, Patrick Townson.
For v.7 (1995) the following people are the source of still even more
comments and information whether direct or indirect:
Mark Brader, Stan Brown, John N. Dreystadt, Pat Duignan, John R. Grout,
Stu Jeffery, John, Martin D Kealey, Basavaraj Patil, Rajgopal Rayru,
Les Reeves, Steve Summit.
For v.8 (Feb 1997): Note that as of this edition, e-mail addresses have
been removed because (a) these change or disappear over time and (b) it
frustrates spammers and other net.vandals and (c) some contributors may
have just wanted to contribute an item or two, and are not full-fledged
telecom experts to be approached by the general public.
The following people are the source of still even more comments and
information whether direct or indirect for v.8:
Avi Chami, Paul Dundas, Kimmo Ketolainen, Susan Kleinmann.
( end of list )
---------
Send future Frequently Asked Questions direct to the addresses mentioned
at the beginning of this document. Do NOT use any of the TELECOM Digest
addresses for correspondence regarding the FAQ unless all the other FAQ
addresses are unreachable.
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% From: [email protected] (TELECOM Digest Editor)
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% To: [email protected]
% Subject: Telecom Frequently Asked Questions File - 1997 Edition
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