Siemens Brothers Neophone 312

Novice collectors are often baffled by these 200-type telephones with 300-series numbers on the paster diagrams but that’s because Siemens Brothers (SB) had their own numbering system. The company named all of their 200 style telephones: Neophones.

The Type 312 is a one-piece instrument with a larger case than the Siemens 300 style telephone and built-in ringer.  The case mouldings are also much ‘sharper’ than the rounded edges of the 310.

The Type 312 is also known as the Universal Neophone.

The handset was identical to the BPO No. 164 design with the normal ‘spit cup’ over the microphone.

Black, brown, walnut and possibly others.

These telephones saw widespread use on private systems installed by  Siemens Brothers Private Telephone Department, in a number of countries abroad.

Further information:
Engineering Supplement to the Siemens Magazine, October 1931; Siemens Brothers Neophone Type 300, pamphlet no. 509A, July 1932, held in the BT Museum, London.

Converting to UK Plug and Socket system

Parts List for 312


312 Paster Diagram

Conversion to UK Plug and Socket

To wire a Type 312 to the UK telephone socket system follow these instructions.  It is illegal to connect unapproved apparatus to any public network.

  1. Remove existing line cord (if fitted).
  2. The Bellset should remain wired to the phone as per the 312 diagram.
  3. Remove one wire from the capacitor (square grey box on the bellset) and insulate.
  4. Remove any wire link found between L1 and E.
  5. Insert 3.3k resistor between Bellset L1 and E.
  6. Terminate the white wire of the line cord on Bellset L1.
  7. Terminate the blue wire of the line cord on Bellset C.
  8. Terminate the red wire of the line cord on Bellset L2.
  9. Insulate the green wire of the line cord.
  10. Connect the rectifier element across telephone terminals 5 and 6.

If you wish to use the telephone without the bell - because old mechanical ringers can sometimes cause problems - then leave out the resistor and wire strap.

It may also be desirable to also modify the telephone as recommended in the section on how the convert to PST.

Additional Pictures

Very rare - mottled brown 312 made for the Manitoba Telephone System

In the picture above and all that follow the phone has a No.10 dial is marked S-36, a capacitor marked S-37 and the bell mechanism is S-38. Interestingly, the screws that hold the feet on also attach the base to the body!
Inside the 312 model phone
312 with base removed
312 base plate





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Last revised: February 22, 2023