Plastic cased table table telephone for use on automatic exchanges.

These were generally used on Private Automatic Exchanges (PAX) in the UK.

Circuit diagram No. L532771 (Model L11750A7).

Although looking somewhat similar to the GPO Telephone No. 706 this telephone was completely different internally.  The circuitry is actually based on the principles of the GPO 300 type telephone.

It is thought that this model was introduced to use up telephone 300 type components, that were now redundant, due to the introduction of the GPO Telephone No. 706.

The differences externally to the GPO Telephone No. 706 were the ATE dial, round plungers and a plug ended line cord.

The case is removed by releasing the two screws found under the handset.

This telephone is also known as the A.T.E. Model No. 6 - click here for more information


Externally the ATE dial is the only difference




The case has a metal clamp (left), a 300 type telephone induction coil and the bell is a single gong.
In this picture the metal chassis has been removed.


The chassis frame is fixed by four screws to the telephone base and this also supports the dial,
gravity switch hook springs and bell ringer mechanism.
The casing is fixed to this chassis by two screws located under the handset.

Conversion to work on the UK Plug and Socket system
 The original line cord is discarded and a new cord with the BT style plug is used.

  1. Remove and discard the original line cord.
  2. Remove strap T3 - T4.
  3. Remove strap T4 - T5.
  4. Insert strap T14 - T15.
  5. Red wire of line cord to T13.
  6. Blue wire of line cord to T4.
  7. Insert straps T16 - T17 - T18 - T19.
  8. White wire of line cord to T15.
  9. Green wire of line cord is used so insulate the end of the wire with tape.
  10. Insert a 3.3K resistor between T4 - T5.
  11. Insert a Rectifier No. 205 (if needed) between T16 and T17.

The original BT line cord is called a Cord Connecting No 4/502.

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Last revised: November 04, 2022