when did push button phones come out in the uk
Push-button telephone In the UK, a brief excursion from standards, GPO telecoms introduced in 1968 their first push-button telephone, the GPO 726 (Ericsson N2000 series [22]), that used neither pulse dialing nor DTMF tones. It used a DC signalling system comprising a number of rectifier diodes[23] arranged in different polarity configuration according to the button pressed. The 726 also requires a ground wire as well as the usual A and B wires. The irony was that with the few installations, the dial signal still had to be converted to pulses in the host PABX. It is now a rare device.
Rotary dial The first patent for a rotary dial was granted to Almon Brown Strowger (November 29, 1892) as U.S. Patent 486,909, but the commonly known form with holes in the finger wheel was not introduced until ca. 1904.[citation needed] While used in telephone systems of the independent telephone companies, rotary dial service in the Bell System in the United States was not common until the introduction of the Western Electric model 50AL in 1919.[1]