@SUBJECT:Frequently Asked Questions File - V.5

Version 5 of the 'Telecom Frequently Asked Questions' file has been
completed and is submitted here for your review. This file is maintained
by David Leibold <djcl@io.org> who should be contacted regarding all
corrections, suggested additions or other changes.

This file is automatically mailed out to each new subscriber to the
TELECOM Digest mailing list, and appears from time to time in the
Usenet comp.dcom.telecom newsgroup. It can also be located in the
Telecom Archives at lcs.mit.edu.

My thanks go to David for his contined hard work in preparing and
updating this file over the past several years, and if you find it
helpful I hope you will send him a note of thanks also.

New readers of TELECOM Digest/comp.dcom.telecom and the other telecom
forums where this e-journal is distributed including the TELECOM Special
Interest Group on Compuserve and elsewhere are strongly encouraged to
*read this file first, before submitting questions to the Digest.* If
you cannot find the answer here, then by all means, please write, but
the comments appearing below represent questions and answers covered
on a very frequent basis in the Digest.

The Telecom Archives are located at lcs.mit.edu and are accessible
using anonymous ftp or the Telecom Archives Email Information Service.
See the file posted here a few days ago describing the Archives and
how to use the automated information service in more detail.


Patrick Townson

   From: djcl@io.org
   Date: Thu, 10 Mar 94 00:17:42 -0500
   Subject: FAQ 

TELECOM Digest - Frequently Asked Questions - v.5   17 February 1994

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.

Much of the telecom information that is requested can be found in the
TELECOM Digest Archives, which is a collection of text files on
telecom topics. These archives are available for access through the
FTP protocol at lcs.mit.edu. Other archive sites may be available,
plus various FTP mail servers. The monthly posting of the description
of TELECOM Digest should contain specific details on how to access
the Archives.

This list is in the archives under the file name:

         frequently.asked.questions

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.

The index to the Archives should be obtained and kept for reference.
This index has also occasionally appeared as a posting in the Digest.
You should also read the Archives file intro.to.archives to get a
better understanding of how the Archives operate.

A list of terms commonly used in TELECOM Digest may be obtained from
the Archives under the file names glossary.acronyms, glossary.txt and
glossary.phrack.acronyms.

Suggestions for other common questions, or corrections or other amendments
to this file may be made to Telecom.FAQ@f730.n250.z1.fidonet.org (Fido
1:250/730) or djcl@io.org. Note that any of these addresses are subject
to change. This file will be updated as time and circumstances permit;
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.

Thanks to Nathan Glasser, Dan Boehlke and Maurice E. DeVidts and those
other inquiring TELECOM Digest minds for their frequent questions.

For v.3, the following people contributed comments, extra questions
and other updated information:

Alan Barclay, (alan@ukpoit.uucp)
Steve Beaty (Steve.Beaty@ftcollins.ncr.com)
Rick Broadhead (YSAR1111@VM1.YorkU.CA)
Gordon L. Burditt (sneaky.lonestar.org!gordon)
Tad Cook (tad@ssc.UUCP, kt7h@polari.uucp, or 3288544@mcimail.com)
David G. Cantor (dgc@math.ucla.edu)
Tony Harminc (TONY@MCGILL1.BITNET)
Carl Moore (cmoore@brl.mil)
Gary Morris (garym@telesoft.com)
Dan Sahlin (dan@sics.se)

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 the following people are the source of even more comments and
information, whether direct or indirect:

Jack Decker
J. Delancy (jdelancy@tecnet1.jcte.jcs.mil)
Adam M Gaffin (adamg@world.std.com)
Fred R. Goldstein (goldstein@carafe.tay2.dec.com)
Rich Greenberg (richgr@netcom.com)
Emilio Grimaldo (grimaldo@sce.philips.nl)
J. Brad Hicks (mc!Brad_Hicks@mhs.attmail.com)
Chris Labatt-Simon (pribik@rpi.edu)
Fernando A. Lagrana (lagrana@itu.ch)
Andy La Varre (alavarre@ids.net)
Marty Lawlor (mel@roch1.cci.com)
Greg Monti (gmonti@cap.gwu.edu)
Carl Moore (cmoore@brl.mil)
John Paul Morrison (jmorriso@rflab.ee.ubc.ca)
Hans Mulder (hans@cs.kun.nl)
Lars Poulsen (lars@spectrum.CMC.COM)
Paul Renault (renaul2@CAM.ORG)
Robert Shaw (ROBERT.SHAW@itu.ch)
Andy Sherman (andys@internet.sbi.com)
Bill Sohl (whs70@dancer.cc.bellcore.com)
Bruce Sullivan (Bruce_Sullivan++LOCAL+dADR%Nordstrom_6731691@mcimail.com)
A Alan Toscano (atoscano@attmail.com)
Pat Turner KB4GRZ
vantek (vantek@aol.com)
Victor R. Volkman (vvolk@aa.hcia.com)

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

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?
 - 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 800 (or 900) service?
 - 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?
 - How was the country code system developed?
 - What is the correct way to write a telephone number for
   international use?
 - What are the prefix digits used in international dialing?
 - What does NPA, NNX, or NXX mean?
 - What happens when all the telephone numbers run out?
 - How is extra numbering capacity achieved in North America?
 - In North America, why does the long distance dialing within an area
   code often change so that 1 + home area code + number has to be
   dialed, or changed to just seven digits (like a local call)?
 - Is North America really running out of area codes?
 - How will we make room if North American area codes are running out?
 - Have any "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?

Regulatory & Tariffs

 - 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?
 - What is Time T?

Competition

 - Which countries have competitive long distance service?
 - 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 that of a 10XXX+ carrier)?
 - Where can LATA maps be found?

Features

 - What is the calling card "boing" and what is it made of?
 - 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?
 - Where can a Cellular/Mobile Radio mailing list be contacted?
 - How are VCR+ codes generated?
 - Why do movies often use 555-xxxx numbers?
 - Are there cases of local calls across international borders?
 - How can one call 800 numbers from other countries?
 - What's an ObTelecom?

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

---------
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 front line in
   terms of the whole telephone system; dial tone, telephone ringing,
   connection to other telephones, or outside trunks, is done here.

   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.

   Crossbar was the next step in electro-mechanical switching. Rather than the
   rotary/level switches used in step-by-step, connections were completed by
   means of a matrix of connectors. The configuration of crossbar matrix
   elements was under "common control" which could route the call along a
   variety crossbar elements. 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.

   Electronic switches 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 eventually use digital, fully-programmable
   switching, but the eventual goal 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.

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.

   Despite the capabilities of such ESS switches, some phone companies
   are replacing these older generation electronic switches (e.g. ESS or
   SP-1) in favour of digital switches (e.g. DMS).

   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 # (octothorpe or 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) which represented priority levels that could establish
   a phone connection with varying degrees of immediacy, terminating other
   conversations on the network if necessary. FO is the greatest priority,
   normally reserved for the President or very high ranking officials. P has
   a lesser priority, but will still take precedence over calls that are
   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.

   Nowadays, these keys/tones are mainly used in special applications such
   as amateur radio repeaters for their signalling/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: 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 set rule is used in
   determining such numbers other than that these are often assigned
   to codes outside normal customer number sequences and would not
   be in conflict with regular telephone numbers.

   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.

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.

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 (i.e. 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).

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 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;
   in recent months, a CAD$50 charge 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
   be applicable outside their service area (provinces of Ontario and
   Quebec, parts of the Northwest Territories).

   An electronic Caller ID construction project was expected to be
   published in 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 videoconferencing and data
   transmission applications, since it carries data twice as fast as
   even the forthcoming 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 800 (or 900) service?

A: The ANI (Automatic Number Identification) feature for toll free (800)
   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 or 900 number.

   As for the precise method of delivering the number to the called
   800 or 900 party, and more details on 800/900 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.

Q: Is there some way I can use a modem to send text messages to my
   alphanumeric pager?

A: (courtesy J. Brad Hicks (mc!Brad_Hicks@mhs.attmail.com))

   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 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 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 071 or 081
   for London, or 021 for Birmingham). Digits other than 0 (generally 2
   through 9) would then represent the initial digit of local numbers.

   In France, there are currently two areas; Paris and everything else.
   All local numbers in France have eight digits. Paris uses an area code of
   1, the rest of the country has no area code as such (just the local
   number, which does not begin with a 1). Long distance access is 16 plus
   the number for regions outside Paris, or for Paris, access is
   16 + 1 + Paris number (this is expected to change to 0 + 1 + number,
   consistent with most of Europe). There are reports that all areas of
   France will be under a single-digit area code in 1995, meaning that
   Paris will retain its 1 area code, but areas outside Paris will have
   an area code assigned to the 8-digit local numbers.

   Some countries do not use an area code; instead, the local number is
   unique within the country. This often occurs in small nations but such
   plans are also active in Denmark and Singapore. Hong Kong got rid of its
   area codes in recent years and converted to seven-digit local numbers.

   North America is unusual in the world in that the long distance access
   code 1 is commonly used before dialing an area codes plus local number
   (or in most areas, at least until the expansion to new format of area
   codes is in effect, 1 plus number for numbers within an area code). Most
   countries include the prefix in their STD codes listing (021 Birmingham,
   UK; 90 Helsinki, Finland) so that an initial prefix code is avoided.
   North American area codes have three digits, while local numbers have
   seven.

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 are still
   in use today). 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) 870-2372     + 1 416 870 2372
    Paris, France    (1) 33.33.33.33    + 33 1 33 33 33 33
    Lyon, France     77.77.77.77        + 33 77 77 77 77
    Birmingham, UK   (021) 123 4567     + 44 21 123 4567
    Colon, Panama    41-2345            + 507 41 2345
    Tokyo, Japan     (03) 4567 8901     + 81 3 4567 8901

   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 Finland or Colombia). 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 prefix digits 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 Community nations in particular are adopting 00 as the standard
   international access code. Those EC nations not already using 00 will
   soon do so.

   Some of the exceptions to 00 (or recent converts to 00) are:

     Australia @    0011            North America     011
     Colombia       90              Russia            8 W 10
     Denmark @      009             Spain @           07
     Finland @      990             Nigeria           009
     France @       19 W            Papua New Guinea  05
     Ireland        00 (was 16)     Sweden @          009
     Mexico +       98              Turkey            00 (was 9 W 9)
     Netherlands @  00 (was 09 W)   United Kingdom @  010
     Norway @       095

  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.

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?

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). Extra area/STD codes can be assigned, such as
   splitting a region's codes (London UK was originally STD code 01, now
   split to 071 and 081; Los Angeles in the U.S. was originally area code
   213, then split to add an 818 area, and recently another split of 213
   created the new 310 area).

   Internationally, telephone numbers may 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. This limit will be increased to
   15 digits in total at "Time T", namely 31 December 1996, 2359 hours
   UTC (GMT), as referred to by ITU-T. There are reports that some 13-digit
   international numbers are already in use, requiring manual or special
   handling by those telephone companies that are set up for only 12 digits.

Q: How is 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 can
         accommodate new prefixes, or

      2) allowing extra prefixes to be assigned by changing from
         NNX format to NXX 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 is not
   widely 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) are 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 does the long distance dialing within an
   area code often change so that 1 + home area code + number has
   to be dialed, or changed to just seven digits (like a local call)?

A: 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

   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) will have to make 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 will be lost for all area codes in 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: Is North America really running out of area codes?

A: Indeed, apart from special "non-geographic" area codes such as 200, 300,
   400 or 500, there are no longer any area codes that can be assigned from
   the traditional format. At present, all area codes have a 0 or 1 as the
   middle digit (212, 907, 416, 708, etc.). The 610 code was freed from its
   usage in Canadian TWX/ISDN service (which moved to 600), so that the split
   of area 215 in Philadelphia can use 610. There remains the assignment of
   code 710 which 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
   require 1+411 for directory assistance.

Q: How will we make room if North American area codes are running out?

A: Bellcore, which oversees the assignment of area codes and the North
   American Numbering Plan (NANP) in general, recommended that
   "interchangeable" area codes be allowed as of January 1995 (advanced
   from the previous deadline of July 1995) due to unprecedented
   exhaustion of available area codes. That means that there no longer
   need to be a 0 or 1 as the middle digit of an area code, and in fact
   the area code will become NXX format. While some suggest that
   eight-digit local numbers or four-digit area codes be established,
   the interchangeable area code plan that keeps ten digits (area code
   plus subscriber number) has been on the books for many years.

   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.

   The last vacant traditional area code, 910, was recently assigned to
   allow for a split of North Carolina's 919 area code. Area code 610 was
   subsequently assigned to Pennsylvania, to split the 215 (Philadelphia
   region) area code, but 610 is a reassignment from TWX/ISDN/Datalink
   services in Canada. Still, Bellcore expects that NPA capacity is
   sufficient until the January 1995 cutover to interchangeable NPAs.
   The interchangeable area code plan will affect the U.S., Canada and
   Caribbean nations under the NANP.

Q: Have any "interchangeable" area codes been assigned?

A: Yes. The first known such code will be assigned for Alabama: the
   existing area 205 will be split up, with a new 334 area assigned
   effective January 1995. Arizona's 602 area will also split, forming
   the new 520 area for 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. At least one other area code has been
   assigned, but awaited formal announcement.

   The current plan is to assign the N2X and N3X (middle digit 2 or 3, as
   in 520 or 334) to "geographic" area codes, which represent regular
   telephone service to lines in specified regions. N8X and N9X format
   codes will be assigned to "non-geographic" services, or those numbers
   that do not have a specific geographic region and need to be translated
   to regular numbers or handled specially. Examples of non-geographic
   services are the 800 (toll-free) and 900 (special charges) services.

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, it is reported that the digit '1' will be added to some
   of the major codes as of 1995 in order to create extra STD code capacity.
   For instance, London's 071 and 081 codes would be changed to 0171 and
   0181 respectively (internationally, change +44 71 and +44 81 to
   +44 171 and +44 181).

   There are rumours that 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 area codes corresponding to
   particular regions.

   Australia is moving 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 to be phased
   in during the 1990's. New Zealand is also completing 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 local numbers throughout
   Hong Kong.

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.

   Some countries are modifying their numbering plans for various
   reasons. The UK will be inserting a 1 before their geographic area
   codes (e.g. London will change from 71 and 81 to 171 and 181 (or
   to 0171 and 0181 as STD codes)).

   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 will be following suit.

   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. 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 because of subsequent area code requirements.

   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 does
   a variety of things for the telephone system in North America. It
   assigns area codes, develops and sells technical documents relating
   to the operation of the phone system, and does research and
   development on various communications technologies. Recently,
   Bellcore did development on MPEG, a video data compression method
   to allow transmission of entertainment-quality video on a 1.5 Mb/s
   communications link.

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, or +1 908 699 5800
   outside the USA (+1 908 699 0936 is the fax number). A catalogue of
   documents can be ordered through this number.

   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 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
   "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 schedules 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.

--------------------
Regulatory & Tariffs
--------------------

Q: What's this about the FCC starting a modem tax for those
   using modems on phone lines?

A: This is one of those tall urban legends, 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.

   Nevertheless, this proposal, or one even worse, 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 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. In modern equipment, touch
   tone is actually better and cheaper for the phone company
   to administer that the old pulse/rotary dialing system.

   The tone dialing charge can be attributed to the value of
   a demanded service; tone is better, thus a premium can be
   applied for this privilege. Also, it is something of a holdover
   from the days when tone service required extra expense to decode
   with the circuitry originally available. This is especially
   true on crossbar exchanges, or where tone would have to be
   converted to dial pulses as is the case with step-by-step
   exchange equipment. Today, cheap integrated circuits are readily
   available for decoding the tones used in dialing, and are
   a standard part of electronic switching systems.

   Some telephone companies have abandoned a premium charge for tone
   dialing by including this in the regular local service charge. Others
   still hold to 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 real call supervision is unavailable or inconvenient,
   a ploy used by some call billing systems is to 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.

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, even though the non-AT&T companies tend to have more
   freedom to offer custom deals.

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 long distance service?

A: Most countries have a single monopoly telephone company for their
   local and long distance services. Yet, deregulation of telephone
   companies and telecommunications in general 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, satellite and other network services.

   The United States has competition in terms of long distance services
   (i.e. a choice of carriers such as AT&T, MCI, Sprint, Metromedia/ITT,
   Allnet, ATC). This was established 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.).

   The UK has a duopoly long distance situation: British Telecom
   and Mercury can provide long distance services but that could
   be challenged as other companies wish to provide long distance
   services.

   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 and BCRL/Call-Net
   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 result of the appeal was that
   the decision could stand, and that long distance competition may
   proceed.

   New Zealand recently allowed Clear Communications to compete in long
   distance. Australia now has Optus as a long distance competitor. Japan
   has competition in international public long distance services.

   There are initial signs competition in the "local loop", or local
   exchange services, also. Reports from the UK indicate that there is
   significant growth in alternative local services, besides the Mercury/BT
   long distance duopoly (competition of two). Cable companies are touted
   as alternative local phone companies because of the available capacity
   on cable feeds, plus the cable industry's conversion to fibre optic and
   digital technologies. A choice of "dial tone" providers may eventually
   be available to match the availability of competition in long distance
   services.

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 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 is charged extra money.

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.

   An official, full list of these codes was part of Bellcore's Telephone
   Area Code Directory document. Bellcore also maintains a list of these
   Carrier Identification Codes as a separate document (see "How can I
   contact Bellcore?" question for details on purchasing Bellcore documents).

Q: How can I tell who my default carrier is (or that of a 10XXX+
   carrier)?

A: In the U.S., dial 1 700 555.4141, and that should get a recording
   indicating the default carrier. This should be a free call. From
   regular lines, dialing 10XXX + 1 700 555.4141 can yield the
   identifying recordings of other carriers.

   On payphones, AT&T is always 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. Thus on payphones, AT&T's
   recording is heard regardless if what carrier access codes are used
   before 1 700 555.4141. Apparently, no other long distance carrier is
   interested in collecting coin revenues. COCOTs usually handle coin
   calls with self-contained coin billing equipment (and guessing of
   call connection time).

Q: Where can LATA maps be found?

A: LATA (Local Access Transport Area) boundaries can 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).

   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 if necessary)
   + 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: 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, 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 possible way of doing this is to flash your switch-hook briefly,
   see if a dial tone comes on, 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.

   Here are some companies that may offer devices that detect distinctive
   ring patterns and route calls to distinctive lines; these are for the
   North American implementation of this feature.

     * Hello Direct 800 444.3556 (HIHELLO) or (408) 972.1990
     * ITS Communications, Endicott, NY 13760  800 333.0802 (607) 754.6310
     * Know Ideas Inc, (708) 358.0505
     * Lynx Automation, Inc., 2100 196th St SW #144, Lynnwood, WA 98036
       (206) 744.1582.
     * Vive Synergies, 30 West Beaver Creek, Richmond Hill, ON Canada
       (905) 882.6107

   Costs for ring detection devices should be approximately USD $80 to 100.

   The March 1994 edition of Electronics Now magasine has a distinctive
   ring detector project, for those who wish to do it themselves.


-------------
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. Unlisted numbers are not listed, nor are they intended to be
   traced by the general public. 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.

   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.

   Private detectives seem to have other means of getting these
   numbers, but that's another story...

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 dec@dfv.rwth-aachen.de.

   Fidonet has a CELLULAR conference for cellular telephony issues, for
   those with access to that network.

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 data 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 many months
   ago. Programs are also available via FTP sites for VCR+ encoding
   and decoding.

   This topic is more appropriate for a newsgroup that deals with video
   or television.

Q: Why do movies often use 555-xxxx numbers?

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-xxxx numbers are generally
   used for Directory Assistance (though a few exceptions exist for
   800 and 900 service, and occasionally for business services).
   Thus, phone companies will recommend 555-xxxx numbers other than
   the 555.1212 directory assistance number. Dialing such numbers
   usually results in a phone company recording or the directory
   assistance.

   Theoretically, 555 numbers could represent valid service numbers
   outside North America.

Q: Are there cases of local calls across international borders?

A: Yes, mainly between Canada and the U.S. There are several points
   along the New Brunswick (Canada) and Maine (U.S.) border that have
   local calling privileges. St Regis in Quebec has local calling with
   Fort Covington, New York state.

   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. This may
   be possible in other nations, though "local" calling is often
   on a measured billing.

   Technically, calls between the Vatican and Rome could be considered
   a case of international local calling.

Q: How can one call 800 numbers from other countries?

A: 800 or domestic toll-free services are intended for use within a
   nation. 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; the reverse situation is also possible.

   AT&T's USA Direct Service allows calls to North American 800 numbers
   from other countries, providing USA Direct service is available. The
   restriction that only AT&T's 800 numbers could be reached is no longer
   in effect. However, the 800 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 800
   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 numbers that are not otherwise reachable from
   Canadian networks. There are charges for using such 800 bypass,
   however.

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.

( 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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