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
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
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.
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.
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.
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
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 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 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.
Before leaving the principal telephone unattended the Secretary operates a
locking BELL TRANSFER button so that incoming calls are routed direct to the
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.
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.
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.
Rocking armature, replaceable capsule. Sensitivity: +46 db relative to I
dyne/cm2/root mW available power.
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
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)