TELEPHONE No. 55
Co's wall set used on the Strowger Automatic System. Fitted with an
Electro-magnetic receiver. This telephone can also be used on party
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.
Telephone No. 55A was wired to Diagram A.T. 200A and used with automatic subscribers having call meters.
The table equivalent is the Telephone No. 72.
Telephone Includes (Early type to Diagram A.T. 8B):-
Telephone Mark 234 included (1918 diagram)
Telephone included (1928):-
The Receiver, Bell No. 4A has no permanent magnet. The American variant 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 - N155
Here is a picture of the insides of a later 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: August 23, 2021