gec.gif (1164 bytes)GEC 710

GEC 710
Secretarial switching telephone system

  • Up to three telephones can be connected to a single exchange line
  • Comprises a principal telephone and one or two extension telephones
  • Switching between telephones is by press button
  • Incoming calls normally answered at principal and then transferred to extensions as required; alternatively, can be answered at any telephone
  • Calls between extensions and exchange are secret from principal
  • Calls between principal and extensions are secret from exchange; can be made while exchange call is held

The GEC710 secretarial switching-telephone system permits a principal switching telephone and one or two extension telephones to operate from a single exchange line. Exchange calls can be made and received at each telephone as required, and all three telephones can be used for internal intercommunication independent of the exchange. Operation of the system is by press button switches located in the case in front of the cradle.

In business and commercial premises, the GEC710 secretarial switching-telephone system allows incoming calls to be filtered through the principal telephone, usually allocated to a Secretary, and then routed to either extension normally used by Executives. Executives can, however, make calls direct to the exchange without the assistance of the Secretary.
The basic installation is the GEC710 1+1 system which uses one principal (Secretary) telephone and one extension (Executive) telephone. To provide for a second Executive, the installation can be extended to the GEC710 1+2 system by means of a simple conversion. This involves the addition of one Executive's telephone and one adaptor unit in the Secretary's telephone; no alteration is required to existing wiring.

This system also provides private intercommunication between Executives and Secretary. Under all conditions, a call from the exchange can be given priority.

The GEC710 secretarial switching-telephone system has the basic high-quality performance that has made GEC telephones acceptable to Telephone Administrations throughout the world. The component parts have proved their reliability in many millions of telephones already in service. All components are mounted on the base plate and are easily accessible for maintenance after releasing two screws in the cradle; the case is removed without inverting the telephone.

The case is moulded in scratch-resistant temperature-stabilized plastic that is easily cleaned and withstands rigorous use in climatic extremes. The simple lines minimize dust collection. Special attention has been given to ensure that the handset will always return to its correct rest position however carelessly replaced. A handle is fitted across the cradle below the handset to allow easy lifting and carrying of the instrument with one hand.

The handset, moulded in the same material as the case, is light in weight and combines a high degree of user comfort with maximum transmitter efficiency. Its shape ensures that, with the receiver held to the ear normally, the transmitter is located in the most efficient position.

The carbon-granule transmitter and the rocking-armature receiver provide clear speech reproduction with low distortion over a wide speech-frequency range.

Handset Cord Location
The handset cord lead-out point is centred at the rear of the telephone base to allow left- or right-handed operation.

The G.E.C. articulated-trigger dial is used which has a self-compensating action that shows no appreciable variation in pulse ratio after 4 impulses. The dial projects through a self-centring number ring on the case. A wide range of number rings is available, in various languages, to suit the needs of individual Administrations. The finger plate is plastic and coloured to match, or contrast with, the telephone colour.

Cradle Switch
The cradle switch design eliminates any likelihood of sticking plungers. A plastic cover is fitted over the spring contacts to prevent accumulation of dust on the contacts.

Automatic Regulator
An automatic regulator is fitted to each telephone in the system. This is required principally on short lines when the sensitivity of the instrument is such that normal speech reproduction may be uncomfortable to the ear. The regulator is a plug-in unit and if not required it can be rendered inoperative by simply inverting it in its socket.

Press Buttons
The press buttons are clearly marked and well spaced to prevent mis-operation. The acetal-resin plungers operate miniature springsets suitably protected against the ingress of dust.

Exchange calls are indicated by a double-coil ringer which operates from all normal exchange ringing supplies. Buzzers, operating from a low-voltage d.c. supply, are used for signalling between telephones. A low-voltage lamp is provided on all telephones to indicate when the exchange line is in use. It is viewed through a wide-angle lens moulded into the telephone case.

The cords are p.v.c. sheathed, affording protection to the conductors against wear and condensation. All cord ends are firmly secured so that the terminations are not subject to stresses. The colour of the cords matches that of the telephone

Power Supply
The GEC710 secretarial switching-telephone system will operate to any normal automatic or C.B. manual exchange line. For intercommunication and signalling between the telephones, the power is derived either from dry batteries or a mains-operated 6 volt or 12 volt d.c. power supply.

Incoming Calls
Incoming calls normally only ring the bell at the Secretary's telephone; to answer the call, she lifts the handset and presses the EXCHANGE button.

Outgoing Calls
Outgoing calls are made direct from any telephone on the system without the assistance of the Secretary. The user who wishes to make an exchange call lifts the handset and
presses the EXCHANGE button on the telephone. The other users of the system are warned that the exchange line is in use by the glowing of the panel lamp on the front of the telephones.

Transfer of Calls
To transfer a call to an Executive, the Secretary presses the HOLD button and the appropriate EXTENSION CALL button (the ensuing conversation is secret from the waiting call. When the Executive is ready to accept the call, he presses the EXCHANGE button on his telephone and the Secretary replaces her handset. In addition, the Executive's telephones are fitted with HOLD and CALL buttons so that a call can be transferred to the other Executive or returned to the Secretary as desired.

Bell Transfer
Before leaving the principal telephone unattended the Secretary operates a locking BELL TRANSFER button so that incoming calls are routed direct to the Executives.

Exchange Recall
When the system is connected to a P.A.B.X. installation which provides `operator recall' or 'enquiry and transfer' facilities, the EXCHANGE button can be pressed beyond its normal locking point to operate additional spring contacts which provide the necessary signalling condition.

The system can be used to provide internal communication between the three telephones in the system. Connexion is achieved by pressing the appropriate CALL button; the called party simply lifts the handset to complete the connexion, Calling indication is by means of a d.c. buzzer within the telephone case. The intercommunication facility can be used between two telephones while the third is engaged on an exchange call. The internal conversation is secret from the exchange call, and vice versa.

Both Executives' telephones can be connected to an exchange call when required; where secrecy is not required, the Secretary's telephone can also be connected to an exchange conference conversation. All three telephones can be simultaneously connected to an internal intercommunication call.


Abridged Specification

Catalogue Number

Case and handset moulded in A.B.S. high-impact plastic. Three colours available: black, dual grey, ivory.

PVC-covered, cadmium-tinsel-conductor coiled cord, colour to match handset. Held in position by grommets which relieve conductors of any stresses.
Line cord - straight: 135 cm (54 in)
Handset Cord: Coiled, Length 25 cm (10 in) unextended; 170 cm (68 in) extended.

Articulated-trigger type.
Speed: 10 p.p.s.
Break-to-make ratio: 2 to 1 other ratios can be supplied. For C.B. working, a dial-dummy disc replaces the dial.

Receiver inset
Rocking armature, replaceable capsule. Sensitivity: +46 db relative to I dyne/cm2/root mW available power.

Transmitter inset
Carbon granule, replaceable capsule. Sensitivity +30 db relative to 1 mV/dyne/cm2 at 20 dynes/cm2 input.

An automatic volume regulator is fitted to limit speech-signal amplitudes on lines shorter than 400 ohms; introduces virtually no attenuation on longer lines.

Double-coil, d.c. resistance 1000 ohms;
Impedance 2000 1 at 25 c/s, 20 k at 1000 c/s. Accepts ringing currents of between 16 and 30 c/s.
Bells, double gong, harmonizing tones.


D.C. single-coli buzzer, moving armature type; D.C. resistance 55 ohms; operates from D.C. supplies of between 3 and 12 volts.
A signal lamp is fitted to each telephone to indicate when the exchange is in use.

Suitable for use in all climates. Protected against entry of insects.

Complete telephone: 1.7 kg (3.75 lb)
Handset weight: 280 gm (10 oz)

Taken from the GEC Catalogue Leaflet STL23A (1966)

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Last revised: January 30, 2021