TELEPHONE No. 726

First generation DC code 'A' signalling, table telephone with provision for 4 additional press buttons.  Above and below the press buttons are label holders, which measure 38mm x 14mm.

The keypad is arranged in a 2 line, 5 key per line format which is surrounded by a raised circular escutcheon plate, 160mm in diameter, which stands proud of the case.  Telephones suffixed with an L have keys marked with figures and letters whilst those suffixed with an F show figures only,

A signalling earth must be connected to the telephone for DC signalling purposes.  The line is also polarised.

Used in the Langham Exchange market research trial with the first press button telephone being installed on the 10th January 1966.  Click here for pictures of the exchange equipment.

The telephone was produced from a Telephone No. 710 but modified as follows:-

• A push button DC Signalling Unit replaces the dial.

• The dial aperture in the cover is enlarged to cater for the keyset.

• A face plate is clipped over the aperture in the case (106mm diameter).

• The Telephone No. 4/726L is fitted with an 18 way line cord.

This telephone was superseded by the second generation model, the Telephone No. SA10023, which had 3+3+3+1 keypad.

Introduced in 1968 and available in the colour grey only.

These telephones were only used on the following customers premises:-
BP, Harlow.
BP, Britannica House., London
Midland Bank, Lombard St., London
ICI, Aberdeen.
ICI, Brockley.

For more information and a complete description of these experimental telephones, see Telephone No. 728.

Circuit diagram - N826 and LD191 (dated 1965).

Specification - S937.

Supplied by Ericsson, their Models N2001 - N2005.

Additional information

Last revised: July 30, 2025