PAGE No. 14

Intercommunication Telephone Systems

The title although equally applicable to all telephone systems is generally known to apply to one in particular,
and implies a means of communication between the various departments of an office, a factory or any similar restricted area.

The increasing popularity of the telephone proves it to be an acquisition of primary importance to any establishment, and the choice of a system is therefore, a matter for very careful consideration.

When selecting a system the choice lies principally between three, viz., the manual which requires an operator for making the necessary connections, the automatic with mechanical and electrical connecting devices and the one to which the title particularly
applies, whereby the user makes all the necessary switching manipulations.

The manual system is undoubtedly convenient from the users point of view and especially where unusual conditions absolutely necessitates the services of an operator, but it becomes too costly and Intercommunication Telephone arranged for table use
Intercommunication Telephone arranged for wall use generally out of the question where a day and night service is required.

The automatic system eliminates the disadvantages of the manual in so far that it will make connections at all times without
the use of an operator, and where the distances between the various instruments are fairly long it is an excellent proposition.

Where however, the distances between the telephones are comparatively short and the number of instruments required is small,
say up to 20, the intercommunication system, to which this article particularly refers, is economical. For many other reasons its adoption as being the ideal for such cases cannot be overlooked, but in fact should be given primary consideration. It provides the most rapid service of any system yet devised and when secrecy is not of importance the design of these modern Intercommunication Telephones with push-button selectors, has reached the acme of perfection and simplicity. They are rightly described as an automatic system without electrical switching devices.

The Ericsson instruments are designed which, if carefully and correctly installed and manufactured for prolonged service and incorporate a unique design and arrangement of push-button mechanisms which comprise a minimum number of parts of substantial proportions and reliable in operation. These mechanisms, probably better described as auto-reset push button selectors, are mounted
in units of five, thereby providing greater utility for inspection and replacements, and even extension should this be anticipated as being ultimately required.

n1135a.jpg (10722 bytes)
Call and Reply Telephone
Wall Pattern (N1135A)

The casework is made of drawn steel finished with a durable black enamel, and wall and table instruments are alike, the cradle being so arranged that it can easily be converted from one position to the other, thus providing yet another instance of utility in design.

One of the most modern and interesting refinements is the moulded Bakelite micro-telephone.  It is fitted with the latest type of inset transmitter which is widely recognised as of superior transmission efficiency and articulation, and a current polarized inset receiver.  This combination enables the users of small private systems to enjoy the same high quality service as that obtainable on the larger public installations.

These wall or table telephones are available in 5-, 10-, 15- and 20-line sizes.  The circuit is single line with a central
battery, usually of seven cells (3 ringing, 4 speaking) fitted near the centre of the system will give a prolonged and trouble-free service.

When one or two stations are situated at some considerable distance from the main area of installation the cost of cable and instruments, to provide full intercommunication facilities for these stations, may be considered prohibitive.  The Call and Reply Telephones however, are useful and economical and it is generally found that they amply fulfil the necessary service required by such stations; for instance, they can be called by and reply to any other station and can call the station with which they are associated.

n1105a.jpg (13133 bytes)

Call and Reply Telephone
Table Pattern (N1105A)



BACK Home page BT/GPO Telephones Ericsson Telephones Ericsson Home Page Ericsson PABX All Telephone Systems

Last revised: October 04, 2022