TELEPHONE No. 311
Introduced in 1948, this Bakelite cased, combined handset wall telephone (equivalent to the table Telephone No. 310) was used by the BPO in automatic areas on shared service lines with selective ringing and metering.
The telephone had a single press button situated above the dial. Above the single press button is a Label No. 252Q.
The phone has an integral relay, that stopped bell tinkle and two rectifier units. These components are also fitted in a Bellset No. 41A, which was always installed with the table equivalent model, the Telephone No. 310.
Produced in the colours; Black, Chinese Red, Ivory and Jade Green.
Mark 1 & Mark 2 models never existed.
The phone case is released from the back plate by one screw
on the right hand side of the case. The whole body,
complete with chassis, swings open to the left, away from the
back-plate which is fixed to the wall. The back plate on
this telephone has pressed standoffs for the wall mounting.
This phone was superseded by the Telephone No. 321 . The Telephone No. 321 was fitted with a Thermistor (which replaced the relay and rectifier packs). This is a very small component compared to the relay and rectifiers, which greatly reduced the cost of the phone.
Superseded by Telephone No. 711 in 1964.
Circuit diagram - N411.
Diagram for Button labels - N620.
Drawing - 90116.
Last revised: October 30, 2022