telephone for use in C.B. & Automatic
exchange areas on PBX extensions, systems that require
recall facilities and certain extension plans.
This telephone had provision for one button in the case moulding.
There was no call for this telephone so it was not released, the
Telephone No. 321 being used instead.
Diagram for telephone circuit - N431.
Diagram for Button labels - N620.
History, Technical and General Information on 300 type telephones
300 Type telephone circuit
Development of the Bakelite Wall
Keys for use in 300 type Wall and Table Telephones
How to restore Bakelite
Comparison chart of GPO 300 type telephones