Used on Telephone No. 746 to stop outgoing dialled calls.  999 can still be dialled.

The Lock is supplied as a kit of parts (Kit No. 311A) and comes with two keys.  The lock worked in conjunction with a Dial No. 28 which is also installed in the phone.

A replacement telephone is supplied which has a opening for the lock.  The lock is fixed to the chassis.

Kit No. 331A comprises of:-
1 x Lock No. 46A and grommet.
1 x Cover No. 7/DCO/723.
2 x Keys.

Diagram - N859.

Drawing - CD2739.

Lock in situ

Case removed showing chassis fixing


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Last revised: January 18, 2023