In the 1950s auxiliary senders were added for storing more than eight digits, and sending by multi-frequency ( MF ) signaling for direct distance dialing ( DDD ).
12.
Direct distance dialing ( DDD ) was subsequently introduced across the country and by the early 1960s most areas of the Bell System had been converted and it was commonplace in cities and most larger towns.
13.
Direct distance dialing ( DDD ) was first introduced in 1972, just 21 years after its initial introduction in Englewood, New Jersey, and 14 years after introduction to Canada at Toronto and Montreal.
14.
Direct distance dialing was initiated in Canada in 1958, beginning with customers in Toronto and on 1 July of that year the Trans-Canada Microwave system, known as the Trans-Canada Skyway, went into service.
15.
Efforts concentrated more precisely on the Laboratories'prime mission of supporting the Bell System with engineering advances including N-carrier, TD Microwave radio relay, Direct Distance Dialing, E-repeaters, Wire spring relays, and computer network design.
16.
Area codes in Brazil are popularly known as " DDD codes " ( " c�digos DDD " ) or simply " DDD ", from the initials of " direct distance dialing " ( " discagem direta ?dist�ncia " in Portuguese ).
17.
For a short time in the early 1950s, area code 318 was temporarily used, initially by customers in Englewood, New Jersey, participating in the first customer direct distance dialing experiment to reach San Francisco as well as some areas north of the Golden Gate.
18.
As direct distance dialing was rolled out in this area in the 1970s, the eastern NWT, along with a large swath of northwestern Quebec, was shifted to western Quebec's area code 819 . Bell Canada sold its northern service territory to Northwestel in 1992.
19.
The North American Numbering Plan introduced area codes for the eventually continent-wide implementation of direct distance dialing started in 1951 with a first implementation in Englewood, NJ . Many calls from outside the city were placed through an ( 212 ) PE6-5000 ".
20.
As direct distance dialing expanded to a growing number of communities, local numbers ( often four, five or six digits ) were extended to standardized seven-digit AT & T conducted extensive studies of product engineering and efficiency and concluded that push-button dialing was preferable to rotary dialing.
