gec.gif (1164 bytes)GEC
ST 1301 - 1302, ST 1401 - ST 1407, ST 1501 - ST 1504, ST1601 - ST1611,
ST 1701 - ST1720, ST1801 - ST1820, TEL/1G to TEL/4G, TEL/10G, TEL/13G & TEL/14G

Click here for a general description of the Gecophone

Circuit diagrams, identification and how to convert Gecophones to Plug and Socket

TEL/6G/ATT - Gecophone with single press button

Originally these telephones were identified by numbers only or prefixed with a K but after 1948 GEC introduced the ST13xxx, ST14XX, ST15xx, ST16xx, ST17xx and ST18xx series Gecophones.

Then in 1955 GEC decided to renumber all their telephones to start with the prefix TEL.  Please see the table below for more information. 

For some unknown reason Gecophones sometimes do not have the model number printed on the base plate.  A diagram may be found inside which will start with the letters "KS" followed by four figures - this is the diagram number and not the model number.

These phones are made in two types; standard and tropicalised.  The tropicalised telephones can be easily identified by the thick neck of the handset support and mesh over the sound holes in the base plate.  The contact set on tropicalised Gecophones is also different from the standard Gecophone and is set at an angle.

Follow the conversion link above for more identification information.


A table telephone of distinctive appearance, supplied in three models one for use with automatic exchanges, one for use with manually operated central-battery systems, and the Convertible Gecophone, which can be used with magneto, C.B.S. manual, C.B. manual or automatic systems and can easily be converted from any system to any other with the minimum of trouble.  The instruments can be supplied with a neat metal bracket (BR1210) for wall mounting; the line wires are then brought straight to the instrument, the terminal strip and connecting cord being unnecessary.

ST 1503 ST 1603

The Gecophone is a self-contained telephone which has proved its qualities under hardest service conditions.  All components are mounted within the moulded Bakelite case, yet every part is accessible.  The induction coil, cradle switch springset and dial are mounted in the case, which has entry for the handset cord close to the connecting strip the line cord enters through a plastic collar attached to the baseplate, on which the bell and capacitor are mounted, and this complete unit can be separated from the case very easily, exposing all parts.  The shape of the case is such that the instrument can easily be lifted and carried by one hand.

The C.B. telephone is the same as the automatic model, except that a dial dummy replaces the dial.  It can be installed even when a future changeover to automatic switching is anticipated since its conversion to automatic working is a simple operation - the baseplate and dial dummy are removed, a dial is fixed in position and a dial cord is connected to the internal terminal strip, then the baseplate is replaced.

The cradle, with its four short prongs of equal length, combines a robust design with a neat appearance.  The cradle-switch mechanism has been specially designed to eliminate a tendency to stick.  Twin contacts ensure maximum reliability.

The handset is fitted with an inset type transmitter.  The flexible handset cord gives exceedingly long service; the conductors are made from tinsel that withstands 200,000 reciprocations without fracture.

The G.E.C. Trigger dial, adopted by the British Post Office as their standard, is fitted with a stainless steel finger plate which retains its high polish indefinitely.

The four-way Bakelite terminal strip, connecting the line wires to the telephone cord, has moulded separators to provide long leakage paths between terminals.  There are separate entrances for line wires and cord.

Facilities are provided for the operation of two telephones in parallel without bell tinkling during dialling.

The transmitter and receiver are British Post Office standards, and the high efficiency speech circuit gives maximum volume with uniform frequency response and excellent sidetone suppression.

The unfailing efficiency of the G.E.C. trigger dial mechanism (British Post Office Standard) is well known, and a special spark-quenching circuit protects the impulsing contacts during dialling.  If required, a suppression circuit can be fitted to prevent interference with nearby radio receivers during dialling.

G.E.C. telephones for service in tropical climates incorporate various special features, which are the result of long experience.  A shunt may be 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.  When required the shunt is connected by the simple transfer of one wire from one terminal to another.

Ventilation holes in the base (pictured above) and beneath the specially designed cradle permit a circulation of air through the instrument to minimise internal condensation.

All apertures are protected against the ingress of insects.  The special cradle (shown cut away to reveal the ventilation holes) has four short prongs which securely hold the handset and withstand rough handling.

The cradle-switch springset has large insulators to ensure long leakage paths between springs.  Flexible cord conductors are V.I.R. covered and braided overall.  Since textile bindings are not in contact with conductors, moisture absorption cannot cause leakage.

Metal parts are specially finished and all wiring is specially made to resist the effects of high humidity and salt-laden atmospheres.  All coils are specially treated to render them impervious to damp, heat and sudden changes of temperature.

For very dusty atmospheres, a transparent plastic cover can be fitted to the back of the dial to give complete enclosure to the mechanism.

The Gecophone Convertible Telephone is designed for the widest applications, provision being made for convertibility by means of variable terminal strapping and external terminal strip connexions.  The telephone can be arranged for magneto working and later converted to or through C.B.S. Manual, C.B. Manual, and Automatic working.  Converting from one system is very simple: strap connexions are altered and, if changing from magneto to C.B. or automatic working, the separate magneto generator box is disconnected and removed.

Ships' telephones are normally ivory in colour with cords finished to match and are fitted with an A.C. buzzer in place of the usual bell.

A multi-way plug may be fitted in place of the terminal strip, if required.

Standard pattern Gecophones are supplied in black only.  Tropical pattern Gecophones are normally black, but can be supplied in ivory, jade green or Chinese red with cords and terminal strips finished to match.  For ordering please quote the colour required after the Catalogue Number.

A magneto extension bell in the G.E.C. Catalogue No. BE1100 series (Standard) or BE1200 series (Tropical), is recommended for use with the Gecophone, to provide calling signals at a distant point, indoors or out, or to augment calling signals in very noisy surroundings.

Characters to appear on the dial number plate
For Non-Director areas the dial is numbered 0, 9 . . . . . unless otherwise specified.
For Director areas the dial is numbered 0, 9 - 1 and the alphabet.


Table Wall Table Wall
ST 1301
ST 1302
ST 1401
ST 1402
C.B. Manual
- - ST 1406
ST 1407
C.B. Manual:- Ships' telephone
ST 1501
ST 1502
ST 1601
ST 1602
Automatic:- for D.C. Ringing*
ST 1503
ST 1504
ST 1603
ST 1604
Automatic:- for A.C. Ringing
- - ST 1610
ST 1611
Automatic:- for A.C. Ringing Ships' telephone

* Note:- For use with the 10-line All Relay P.A.X., Cat. No. PX1110 (Standard) and PX1210 (Tropical).


Table Wall Table Wall
ST 1701
ST 1702
ST 1801
ST 1802
Magneto:- regular or with capacitor auto-clearing
ST 1703
ST 1704
ST 1803
ST 1804
Magneto:- loop auto-clearing
ST 1705
ST 1706
ST 1805
ST 1806
Magneto:- earth auto-clearing
ST 1707
ST 1708
ST 1807
ST 1808
Magneto:- R.S.A.X. with earth-clearing
ST 1709
ST 1710
ST 1809
ST 1810
Magneto:- with earth ring-off key
ST 1711
ST 1712
ST 1811
ST 1812
C.B.S. Manual No. 1
ST 1713
ST 1714
ST 1813
ST 1814
Party Line, C.B.S. Manual No. 1
ST 1715
ST 1716
ST 1815
ST 1816
C.B.S. Manual Nos. 2 and 3
ST 1717
ST 1718
ST 1817
ST 1818
C.B. Manual
ST 1719
ST 1720
ST 1819
ST 1820

Convertible Gecophones arranged for Magneto working each require a 3-volt battery.  G.E.C. Dry Cells, Catalogue No. BA4955, are particularly suitable for this purpose and are suitable for service in either temperate or tropical climates.

9" x 6.3" x 5.8" (23 x 16.3 x 15 cms.)

Standard pattern, 5 lb. 13 ozs. (2.64 kgs.)
Tropical pattern, 6 lb. (2.72 kgs.)

Taken from the GEC Catalogue Leaflet No. STL 9


Note the neck on both phones - the ST1503 (pictured to the left) is standard whilst the ST1603 (pictured to the right) is much larger with the tropical ventilation holes inside
ST1401 Base plate
ST1401 rear view
ST1401 internal view
Note the angled contact set
ST1301 - Bell fitted
ST 1503 Internal
ST 1603 Internal
ST 1603 Internal
ST 1603 Exterior view
ST 1603 base plate exterior
ST 1610 inside the case
ST 1610 Base plate showing buzzer instead of a bell
ST 1610 showing sound holes covered with mesh - Tropicalised


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Last revised: January 10, 2023