The Trimphone was introduced by the General Post Office in the 1960s as an alternative to standard telephones such as the 706. The Trimphone had a number of features that made it stand out from the standard telephones, and hence customers had to pay extra for one!
The Trimphone had a more fashionable, slimmer design compared to the likes of the 706 and 746, and was much lighter. However, the lighter weight did end up causing issues with customers with the telephone sliding about when being used, especially when dialing.
The most notable change though was the sound, the Trimphone had a distinctive warble for it's ringer using electronics rather than the bell on earlier telephones. The Trimphone also has an illuminated dial (thanks to some mildly radioactive substance in the dial!) The Trim in Trimphone is in fact an acronym for Tone Ring Illuminator Model. The Trimphone was released as the 712 and 712L (with a lettered dial) in the mid-1960s in limited areas, and nationwide in 1968.
Production switched to the 722 and 722L models which had a number of improvements and refinements. Production of the Trimphone continued until 1982. We have two Trimphones, a grey 722 and a green 722L with a two colour dial.
