INTERCOMMUNICATION
TELEPHONE SYSTEMS

An intercommunication telephone system may be used with advantage in offices, workshop s etc. where the cost of a manual or automatic exchange is prohibitive. Intercommunication telephone systems are manufactured on the one hand for internal traffic only, on the other for internal and external traffic, i.e. with exchange lines to the public network.

INTERCOMMUNICATION TELEPHONE SYSTEMS
FOR INTERNAL TRAFFIC

General
Two types of these systems are supplied, one for maximum 10 instruments (DEH 1210, DEN 1110) and one for maximum 20 instruments (DEH 1220, DEN 1120). They are well suited to situations where several calls are required to take place simultaneously. The system cannot be connected to the public telephone network, but its flexibility makes it a useful supplement to a private branch exchange.

If only one call at a time is needed, a domestic telephone system may be recommended.

The application of intercommunication telephone systems is limited by the number of instruments and line distances. When distances between instruments are considerable, the cost of wiring will be excessive.

Every station can call any other station. The instruments are provided with a knob (selecting switch), which is turned to the required number.

Calling is effected by means of a push button.

• The system is permanently in operation - the caller connects his own call.

• No limit to the number of calls.

• The calls are non-secret- connection is always established.

• Central battery system- battery eliminator or if necessary a battery.

• The flexibility of the system makes it easily adaptable to the lay-out of the organization.

The instruments specified below cannot be connected to local battery intercommunication systems of obsolete type. For extensions of such systems quotations should be asked for from case to case. A n intercommunication system consists of instruments, wiring and battery eliminator (or dry cell battery).

Instruments for 10-extension line intercommunication system are intended for small installations.  Desk and wall instruments are available.

Instrument for 20-extension line intercommunication system are intended for large-sized installations, but may also be used for small installations if future extensions are anticipated. Desk and wall instruments are available.

The wiring can be carried out in any conventional cable material. Cable EEB 22 x 0.5mm and 42 x 0.5mm respectively is recommended, even if the system initially is not extended to full capacity. The line distance between extreme instruments may amount to 500 metres.

A battery eliminator is preferable under normal conditions providing the mains are reliable - the system cannot be used in case of mains failure.

Batteries give more reliable service, but are more expensive to maintain than a battery eliminator.  A suitable battery consists of eight dry cells

BKA 2002 in two battery boxes BKY 1003.

Other types may be used.

The instruments are connected by means of a multicore cable. Generally the cable is run from station to station. When branching is required, junction boxes NEC 6001 for 10 lines or NEC 6002 for 20 lines are used.

Instruments for 10 lines: DEH 1210 (desk), DEN 1110 (wall).

Instruments for 20 lines: DEH 1220 (desk), DEN 1120 (wall).