Need ITU-T E.123 summary

Skip to first unread message

Frank Vance

Mar 24, 1994, 3:33:20 PM3/24/94
Can someone summarize the salient points about ITU-T recommendation E-123?
What is the correct way to represent a telephone number?

Frank Vance +1.713.963.2426 Western Geophysical 10001 Richmond Avenue
Fax: +1.713.963.2758 Houston, TX 77042 USA

Markus Kuhn

Mar 25, 1994, 3:59:52 AM3/25/94
to (Frank Vance) writes:

>Can someone summarize the salient points about ITU-T recommendation E-123?
>What is the correct way to represent a telephone number?

My telephone number in the FULL E.123 notation looks like this:

national (09131) 52226
Telephone -----------------------------
international +49 9131 52226

This notation (e.g. on letterheads, etc.) is a little bit large, but
is the most understandable representation of a phone number for most

Or you can also only use the international notation +49 9131 52226.
The phone number consists of 3 parts, the first one is the country code
(49 for Germany). The single + shall remind the reader that a national
prefix has to be added to the number. The recommended ITU prefix
(as defined in E.163) is 00 which is used in most countries,
but there are also other prefixes in use (e.g. 19 in France),
so the more generic + is written instead of 00.

E.123 has also a few special definitions for north american phone
numbers were some things are different than in the rest of the world.
I don't remember the details, but I can look them up, if you are
interested. There are also some special symbols for waiting on a
dial tone (I think it was ~) and for answering machines defined.
E.123 is about 4 A4 pages long. If they haven't alread available E.123
in digital form on gopher, then you might ask for it
at and perhaps they'll process it with higher


Markus Kuhn, Computer Science student 城o偵 University of Erlangen, Germany
Internet: | X.500 entry available

Erik Naggum

Mar 26, 1994, 6:43:08 AM3/26/94
[Frank Vance]

| Can someone summarize the salient points about ITU-T recommendation
| E-123? What is the correct way to represent a telephone number?

ITU recommendation E.123 (1988 edition in the Blue book)

1. General
1.1 (specifies visual layout properties)
1.2 (specifies use of the words "national" and "international")
1.3 (specifies use of the symbol or word for "telephone")
1.4 (specifies "within N. Amer. zone")
1.5 (specifies omitting the national part for only international numbers)

Telephone International +22 607 123 4567

1.6 (specifies the use of the word "extension" or abbreviation thereof)

Telephone International +22 607 123 4567 ext. 876

2 Classes of symbols
(lists diallable, procedural, information and spacing symbols)

3 Diallable symbols
(specifies symbols that occurs on a telephone set, digits, letters,
other signs. annex A gives more information)

4 Procedural symbols
4.1 International prefix symbol (plus, +)
(serves to remind user and identify number as international)
4.2 Use of parentheses
(should enclose digits that are not always dialled)
"The ( ) should not be used in an international number."
4.3 Multiple numbers reached through automatic search
4.4 Multiple numbers without automatic search
(IMNSHO: upgrade to a PABX, and save the caller the trouble)
4.5 In-dialling
(dots in the number indicate an internal extension number)
(spacing should otherwise conform to national convention)
4.6 Symbol to indicate the existence of an additional dial tone (tilde, ~)
(IMNSHO: avoid calling countries where this is required)

5 Information symbols
(answering machines, etc)

6 Spacing symbols
6.1 (spaces should be used unless procedural purposes intervene)
"Only spaces should be used in an international number."
Footnote: "Administrations [including RPOAs] using dots or hyphens as
separators nationally may require time to determine the consequences of
discontinuing their use." (this only means that some countries (most
notably France) whined until this provision was accepted)
(IMNSHO: dots and hyphens are for weenies)
6.2 "In the international number, spacing shall occur between the country
code and the trunk code and between the trunk code and the subscriber
number." (does not preclude other space)
6.3 (separation should be larger between trunk code and local number)
(IMNSHO: useless, and it has not been followed in previous examples)

7 Facsimile number notation
(use the symbol/word "FAX")

Annex A Desirable properties of diallable symbols

A.1 Distinct from other diallable symbols
A.1.1 (visually distinct)
A.1.2 (aurally distinct)

A.2 Widely known name
(IMNSHO: takes all the fun out of "splat" and "octothorpe")
A.3 Reproducible
A.4 CCITT-ISO compatible
(CCITT Alphabet No 5 and ISO 646 must include the symbol)
A.5 Made up of single character
A.6 Abstract
(no existing intrinsic meaning from other specialized use)
A.7 Immediately recognizable as a diallable character
(should not conflict with procedural or information symbols)

following this recommendation to the letter, my international phone number
is written

Telephone International +47 22 95 03 13

however, since people on the Net are smarter than the rest, and because I
don't play Bingo (tm) with phone numbers (which looks _so_ stupid when you
list four or five phone number), I prefer larger units and omit the
"Telephone International" part:

+47 2295 0313

(Norway abolished the trunk code and now only has 8-digit numbers. other
countries should realize the enormous benefits of this and throw out their
"trunk codes". also, a constant number of digits in the phone number helps
make sure you have the right number. Germany and Sweden should realize
this and abolish their silly variable-length numbers, some of which are so
long you can't call them internationally!)

where I edit contributions from North American contributors, I always
harmonize their phone numbers from the various notations used:

(607) 555-6789
(607) 555 6789
1 607 555 6789
1-800 555 1234
(800) 555 1234 // there is no _area_ for "area code" 800!


+1 607 555 6789
+1 800 555 1234

your number would be transformed from the _very_ unusual "+1.713.963.2426"
(which looks like a mal-formed IP address to me, just as the French numbers
appear to be IP addresses) into "+1 713 963 2426".

thanks for asking. hope this helps. you may not agree with the IMNSHO's,
but you can easily remove them from the summary.

best regards,
Erik Naggum <> <> | memento, terrigena.
ISO 8879 SGML, ISO 10744 HyTime, ISO 10646 UCS | memento, vita brevis.

for information on SGML and HyTime, try first.

Reply all
Reply to author
0 new messages