TELEPHONE No. 55
Co's wall set used on the Strowger Automatic System. Fitted with an
It is the phone used by the GPO on the two auto exchanges introduced in 1912 (Epsom, Surrey and the Official Switch [i.e. Post Office Headquarters] in London).
Also known as the Epsom type.
Very basic circuit, with dial, Receiver Bell No. 4 and transmitter all in series with no induction coil.
The Receiver Bell No. 4A has no permanent magnet. The American make has a Diaphragm No. 9 and an Earpiece No. 4, whilst the Mark 234 has a Diaphragm No. 12 and an Earpiece No. 2.
Sometimes fitted to a Desk No. 4.
Circuit diagram - N155Original diagram - AT 8.
Here is a picture of the insides of a Telephone No. 55. All the brassware should be black and note the non-ATE dial, especially the way it is fixed!
You are warned that this telephone has a very basic transmission circuit which is nothing like the quality of a modern telephone. The wiring is also non-standard and may tinkle bells on your premises, when dialling out.
Last revised: December 01, 2018