History of the Telephone Number: All-Number Calling

As discussed in the first part ("History of the Telephone Number: Early Years") of this series, telephone numbers through the first half of the twentieth century used the 2L-5N system (two letters and five numbers). The two letters of the telephone numbers corresponded to a memorable word, such as BUtterfield or ANdrew. As demand grew following World War II, however, limitations in this system quickly became apparent. The numeral 1 was reserved for long-distance dialing, and 0 was reserved for the operator. Several combinations, such as 57 and 97, were unusable because it was impossible to make a corresponding word.

The Bell System split some area codes to allow reuse of numbers, which worked for a time - only two new area codes were added between 1962 and 1981. Nonetheless, in 1958, AT&T began the slow transition to all-number calling (ANC), gradually replacing the letters with numbers. All-number calling was first implemented in smaller communities; Wichita Falls, Texas, was the first to complete the conversion in 1958.

AT&T used a three-stage process to ease the transition. At first, telephone directories printed the full word associated with the exchange; e.g., BUtterfield 5-6861. In phase one, the letter exchange was printed without the associated word: BU 5-6861. In phase two, those still using five or fewer digits were brought up to seven. In the third, printed directories showed only the seven-digit number: 285-6861.

By 1965, all new phone numbers conformed to all-number calling, but the nationwide transition lasted well into the early 80s. Opposition was strong in some larger cities; groups, such as San Francisco's Anti Digit Dialing League, organized against the new system. Some people considered their ROckwell or WHitney letter exchange as part of their identity, or at the least useful in identifying where a caller was located. Newspaper editorials were written protesting the change, and at least one protest song was recorded, in 1966. New York City did not convert fully to ANC until 1978, and one Philadelphia directory still listed alphanumeric prefixes as late as 1983.

Interestingly, the use of the 555 prefix in movies and television began in this area, originally as KLondike 5. The 555 prefix was reserved for the telephone company, and generally used only for directory assistance (555-1212). Movie and television writers began using it as a way to avoid generating any unwanted calls to an existing number (as famously happened with the 1982 song, "867-5309/Jenny").

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