GEC MURAPHONE
ST2301 - ST2316, ST2401 - ST2416, ST2501 - ST2516, ST2601 - ST2616 and TEL/1M, TEL/2M, TEL/6M & TEL/8M

The original part numbers for the Muraphone was two (Catalogue No. 89) or three digit numbers (GEC Magazine) but in 1946 the phones were re-numbered ST 23xx, ST 24xx, ST 25xx and ST 26xx series and again in1955 GEC decided to renumber all their telephones with the prefix TEL.  Please see the table below and also follow the link called "click here for general information".

Click here for general information on the Muraphone

Click here for the Muraphone K - updated Muraphone with new style handset and circuitry

Click here for information on how to convert your Muraphone to Plug and Socket

Click here for Muraphone circuit diagrams

GEC Current Comments Article

The picture shown to the right is the earlier Muraphone, which easily identifiable by the spittoon mouthpiece.  The later version, known as the Muraphone K, has the modern curved handset, without the spittoon mouthpiece.

THE GEC MURAPHONE

Application
A wall-mounting telephone for use with all automatic or C.B. manual systems. Designed in two slightly-different types, one for the usual public service systems and the other for hotels, service flats and passenger vessels.

Construction
The case is a plastic moulding, in either black or a selected colour. It is shaped to form a cradle for the receiver and a housing for the transmitter, so that the handset is securely held in a vertical position. The front surface is the correct width to accommodate a dial, and the circular motif is repeated at the sides of the moulding by concentric segments. These are provided with sound-outlet apertures for the bell or buzzer with which the Muraphone may be fitted.

The cradle switch is extremely positive in action, and is operated by a lever on which the receiver rests when the handset is in position. Rollers, attached to the switch lever, actuate the switch springs. These are provided with twin contacts, and the leverage obtainable allows contact pressures to be greater than in plunger-type cradle-switches.

The G.E.C. dial is the British Post Office standard, with stainless steel fingerplate. It is fixed to a special support, so that the case can be removed entirely. The C.B. Muraphone for public systems is convertible to automatic working by the removal of the dial dummy, replacement by a dial, and connexion of a dial cord.

The terminal strip, mounted at the lower end of the unit, terminates line wires, handset cord and dial cord on screw terminals, which are separated by moulded insulators to prevent surface leakage. A tight-fitting rubber bush anchors the handset cord to the terminal strip. This arrangement relieves the conductors of the strain from a direct pull, seals the point of entry, and allows the cord maximum flexibility without the possibility of frayed braiding.

For Ships, Hotels, Flats, etc.
For the model specially designed for ships, hotels and flats the subdued note of the buzzer is generally preferred to the louder ring of the bell, and plunger-type terminals replace the screw-type for line wires. Line wiring can be concealed in the decorations and terminated on a small connexion block, which is provided with sockets to take the plunger terminals when the Muraphone is fixed to the wall. This type of Muraphone can thus be plugged in to existing wiring as required.

Because the systems for which it is designed are not likely to change from manual to automatic operation, the C.B. version is not designed to allow the quick fitting of a dial.

The B.P.O. standard inset-type transmitter and receiver are included in a high-efficiency speech circuit which gives the intelligibility that results from the maximum suppression of sidetone.

A spark-quench circuit protects the dial impulse springs.

If required, a suppression circuit can be included to prevent interference with nearby radio receivers during dialling.

Tropical Models
The tropical Muraphone incorporates special features which are the result of long experience

• A shunt is connected across the transmitter to minimise the minute arcing that tends to occur at the granules and electrodes as the cradle switch operates the accelerated tendency towards frying often shown by transmitters in the tropics is thereby offset. The effect of any increase in transmitter resistance upon line circuit conditions is also minimised by the shunt. The loss in volume efficiency is very small and is partly cancelled by reduction of sidetone, the net result being a difference of only 1db. 

• Apertures in the case are covered with fine wire gauze to prevent the ingress of insects. 

• Metal parts and all wiring are specially finished and treated to resist the effects of high-humidity atmospheres. 

• Cradle-switch springs are covered with varnish to maintain insulation resistance. 

• Flexible conductors are V.I.R. covered and braided overall. 

• All coils are specially treated to render them impervious to damp, heat, and sudden variations of temperature. 

• For very dusty atmospheres, a Bakelite cover can be fitted to the back of the dial, giving complete enclosure of the mechanism.

Colours
The standard colour is Black, but enquiries are invited for the telephone in Ivory, Jade Green or Chinese Red, with cords finished to match.

Connexions
Connexion Block for line wiring for Muraphones with plunger terminals - Cat. No. CBI 101.

Dimensions
Height, 9.3" (25cms) 
Width, 5.3" (14cms) 
Depth (over handset), 5.75" (15cms)

Weight
Average of all models, 4.25lbs. (l.9kgs.)

Taken from the Catalogue Leaflet No. STL.7

Pre 1955 Catalogue Numbers

1955 CATALOGUE NUMBER CONVERSION TABLE

ADDITIONAL INFORMATION AND PICTURES

These are pictures are of the original Muraphone - easily identified by the spittoon mouthpiece

ST2301 - CB version	ST2502 - Auto version
ST2510 Internal view	ST2510 External view
Early picture of the terminal block connector model - note no screw terminals for L1, L2 or E, as the block connects to the rear	Same telephone shown to the left, but with the dial removed to expose all components that are mounted on the base plate

ST2404

Front view.  The grey cord and terminal block were not originally supllied

Front view showing the earlier spittoon style handset

View of base plate showing original feet
The wall fixing screws went through the centre of the feet

TEL/1M/AWS

TEL/2M/CWT

In the picture above, the feet are fixed by screws - the feet on this phone have been replaced.

Last revised: August 01, 2025