All-number calling

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All-number calling (ANC) is a telephone numbering plan that was introduced by the Bell System in the United States starting around 1958 to replace the previous system of using a telephone exchange name as the first part of a telephone number.

Bell System mapping of letters to dialed digits in the 1950s
dialed digit letters
1
2 A B C
3 D E F
4 G H I
5 J K L
6 M N O
7 P R S
8 T U V
9 W X Y
0 Z

Until the 1950s, a typical telephone number in the United States and many other countries consisted of a telephone exchange name and a 4 or 5-digit subscriber number. The first two or three letters of the exchange name translated into digits given by a mapping typically displayed on the telephone's rotary dial by grouping the letters around the assigned digit. The table (right) shows the typical assignment in the Bell System in use until the late 1950s. The letter Q was not used, and Z was translated to 0 (zero) on some dials, albeit never used in the name system. For example, a New Yorker's phone number might have been CHelsea 4-5034, which another telephone subscriber would dial as the digit sequence 2445034, translating C to 2, and H to 4.

After World War II, and particularly in the 1950s and 1960s, demand for telephone service strained not only the resources of the telephone operators, but also the network system of telephone exchanges and the traditional numbering plan using telephone exchange names. It was necessary to begin using digit combinations that could not be expressed by memorable names.

All-number calling was first introduced without much publicity in small communities where it was met with little resistance.[1] In other areas this change sparked an intense outcry among urban users who considered all-digit dialing to be dehumanizing.[2][3]

Opponents created a variety of organizations to oppose all-number calling, including the Anti-Digit Dialing League and the Committee of Ten Million to Oppose All-Number Calling to pressure AT&T to drop the plan.[4]

Other countries introduced similar transitions for eliminating exchange names. In the United Kingdom, the new system was known as all-figure dialling.

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