Everyday Math

Numbers and Math in Everyday Life

Why do we have certain telephone (and cellphone) numbers?

Telephone numbers have a long and numerical history. Starting around 1879 and before the 1920s, most telephone conversations started with cranking a crank, which would “connect” to an operator; from there, the caller would most often either give a person’s name or company and/or address—mainly to other local telephone owners. At this time, too, each customer who had a phone was usually assigned a four digit code, which would be used by the operator to make the call.

After the late 1920s, this progressed to calling the operator and using an “exchange name” to get the party one was calling; in addition, telephones with automatic dialers were becoming vogue in homes, making it easier to dial a number yourself.

But in order to accommodate the many people using the telephone, and to stop the confusion caused by many people living in larger cities having the same names, telephone companies turned to an alternate system of calling another party on the phone. Whether using an operator (usually if a person was not home) or a home dial phone, telephone company AT&T used a combination system of numbers to reach a party, whereas Bell System used a name and number system: the first two letters and number was the switching office or exchange, while the last four numbers represented the customer’s number. For example, the movie Butterfield-8 was actually named after an early exchange name. And, for example, for the Bell System name and number listing, an older number the authors are familiar with began with the colorful “PIoneer 8-XXXX.” No one really knows why the “letters and numbers” began, but it may have been that telephone companies believed that people would remember names better than the correct order of seven numbers.

By 1958 people began asking for their own telephone numbers, phasing out the exchange number/letter system. The first city to use all number calling was Wichita Falls, Texas. It took just over a dozen more years for the letter and numbers to be replaced all over the country. With this code, the first three digits are called the prefix (or exchange number); the last four digits represent the part of the town in which you live. Thus began the familiar area code numbers (to send the phone number to the right state) and seven-digit numbering system with which we’re all familiar.


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