858 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1952 



convenient to use and one which they can use with a very high degree 

 of accuracy will suffice. The need for accuracy is readily apparent since 

 with the customer's telephone being given access to the intertoU network 

 without the intervention of an operator, a call which is misdialed can be 

 routed to a telephone thousands of miles from the desired destination. 



At present customer dialing of toll and multi-unit calls is for the most 

 part confined to situations where the call can be completed by the use 

 of the number as listed in the directory without any additional digits 

 being dialed. In a few cases as from Camden, N. J. to Philadelphia and 

 certain offices in Northern New Jersey to New York City, the code 11 

 is prefixed to the listed number. In the case of the current trial of cus- 

 tomer toll dialing at Englewood, N. J., the customers are using area 

 codes such as 415 for Oakland, Cahfornia, 312 for Chicago, etc., diaUng 

 only into those cities which now have the 2-5 type of numbering. 



From the Englewood experience it can be confidently predicted that 

 this form of dialing, i.e., an area code followed by a telephone number 

 consisting of a uniform number of digits, is one that customers will use 

 with a reasonable degree of convenience and accuracy. The problem 

 therefore to meet the requirements for nationwide customer toll dialing, 

 is to establish universally for all central offices regardless of size and loca- 

 tion a uniform pattern of numbering for toll purposes. The only form of 

 number completely filling the needs is the 2-5 system, which is that used 

 in the largest cities today. 



Accordingly, in order to implement the program for customer dialing 

 of toll calls on a nationwide basis, it will be necessary to place all tele- 

 phone numbers on a 2-5 basis with the code of each office different from 

 that of every other office in the same numbering plan area. Thus each of 

 the 50,000,000 telephones in the United States and Canada will have, for 

 toll dialing purposes, a distinct identity consisting of ten digits; a three- 

 digit area code, an office code of two letters of an office name and a 

 numeral, and four digits of the station number within the office. Typical 

 numbers for toll dialing would therefore be 601-CA3-4567 or 317-MA7- 

 6789. As with operator toll dialing, on a toll call which terminates in the 

 same numbering plan area in which it originates, the area code will be 

 omitted and the office code and station number^ — a, total of seven digits 

 will be used. 



With this universal 2-5 type of number, local calls in and about the 

 larger and medium sized exchanges will be completed by dialing the 

 entire seven-digit number. For many of the smaller places in the more 

 isolated sections, 5-digit or 4-digit dialing will frequently be employed 

 where this number of digits will be adequate for all of the telephones 



