Common Phone Key Pads
There are several different key pads in use today. Essentially, there is the american (Ma Bell) classic, the new ITU/ANSI/ISO/IEC standard, and one former standard each for the UK and Australia. Then, (it probably seemed like a good idea at the time) mobile phone manufacturers invented a whole bunch of new ones.
Fortunately, there is a standard (ITU E.161, also known as ANSI T1.703-1995/1999, and ISO/IEC 9995-8:1994), and most phones built today place letters on the phone key pad according to that standard.
The following table shows how the most common touch tone key pads map letters to numbers.
Common Phone Keypads
There exist a number of variations on these key pads, mostly involving the use of the letters I, O, Q, and Z and the numbers 1 and 0. There are also a number of local variations involing characters found in the scripts of local languages (umlaut's etc).
We are working on a historical database of telephones. Please send us the manufacturers name, year and model number of your phone and tell us what kind of key pad your phone has. If you like, include a picture of your phone. We will incorporate the data in future revisions of our site.
Problems Arising From Assumptions about Key PadsMany IVR (interactive voice response) systems, also known as phone bots, let you enter names using your telephone key pad. This is done, for instance, when looking up a particular extension by name. These systems sometimes overlook the fact that not everybody has the same kind of keypad. So, if you are looking up "Steve Wozniak" in a company directory and are asked to enter the digits corresponding to the first three letters of his last name, you might type 969, 961, or 900, depending on the kind of phone you are using.
North American Classic Key Pad
This is the standard north american letter/number assignment found on Telephones in Canada and the US since beginning of the 20th century. The assignment of numbers to letters predates DTMF and touch dialing and is the same as found on many old rotary dial phones.
North American Classic
Literally all companies building telephones for consumers on that continent used this assignment.
ITU E 1.161 International Standard Key Pad
The second half of the 20th century saw the demise of exchange names and the relaxation of rules on what digits could appear in area codes and exchange prefixes. This, plus the use of touch tone dialing and vanity numbers finally led the telecom industry to come up with places for the remaining letters.
The natural course of progression was to keep the existing phone key pads and dials and to find a place for the letters "Q" and "Z" that was consistent with the classic key pad.
UK Classic Key Pad
This assignment was used predominently in and around England. We assume that he "Q" and "O" were given to the number "0" because they look similar, and also because "O" also stands for "Operator".
It is now largely being displaced by the new international standard key pad.
Australian Classic Key Pad
This used to be the AUSTEL standard phone key pad. Like the others,
it is now being replaced by the internaltional standard.
Outside North America, the "miscellaeous" letters "O", "Q",
and "Z" not found on the classic key pad were given to the
number 0. This is very similar to the old UK standard.
Other Phone Keypads
Some more creative letter arrangements (1 = ABC, 2 = DEF, etc) can be found on some european cellular phones. Europe does not share north america's fascination with old exchange names, and -- more importantly -- vanity numbers are somewhat of a novel concept. Maybe this lack of historical baggage allowed some european cell phone manufacturers to take a fresh approach to assigning letters to numbers.
Manufacturers will probably continue to build phones with these key pads for local markets, but on a world wide basis, most new phones now use the ITU E.161 standard letter assignment.