Trimphone
![A Trimphone, viewed from the side. The handset cradle functioned as a carrying handle when the receiver was off the hook, and the coiled cord in theory allowed the phone to be carried around.](/Images/godic/202502/17/Trimphone4917.jpg")
![The Trimphone, from above, in the original dial design and the later keypad. To fit the electronics used to generate the dial pulses (and in later models, tones), the depth of the case was increased.](/Images/godic/202502/17/TrimphoneDialAndKeypad4917.jpg")
![The Telephone No. 712 usually featured an alphabetical dial, which was also used on early versions of the 722.](/Images/godic/202502/17/TELE712DIAL4917.JPG")
![](/Images/godic/202502/17/1969_GPO_1722F_MOD_Grey_&_Green_Rotary_Dial_Trimphone_Telephone4917.JPG")
The Trimphone is a model of telephone designed in the 1960s in the UK. It was positioned as a more fashionable alternative to the standard telephones available from the GPO, the predecessor to British Telecom. The name is an acronym standing for Tone Ring Illuminator Model, referring to the then innovative electronic ringer ("warbling", as opposed to the traditional bell) and the illuminated dial. The luminous dial or betalight contained the mildly radioactive element tritium, which later caused some concern about safety. At one point during the 1990s the United Kingdom Atomic Energy Authority at Harwell was fined £5,000 by Wantage Magistrates Court for accumulating radioactive waste, having collected several thousand Trimphone luminous dials in a skip.