NATIONAL TELEPHONE COMPANY
BATTERY INTERCOMMUNICATION TELEPHONES
Pattern No. B590
Comprises - Hand Combination Transmitter and Receiver with Double Contact Key, Cord, Automatic Replacement Levers and Automatic Replacement Cradle, Induction Coil, Bell, Push Button and a Pair of Through Connection Plugs.
This instrument has been specially designed to meet the requirements of what is now commonly known as the Reply-and-Call System, which under certain circumstances, has advantages over the ordinary Intercommunication, or Central Station (i.e. a switchboard on which all the lines concentrate) Systems.
With the ordinary Intercommunication System any department can speak to the other at will direct, without requiring a central station. It is, however, sometimes deemed advisable that only the principal should be able to communicate from his office with the various departments, and vice versa; or at any rate that the departments should not be able to communicate With each other without the knowledge of the principal, while the latter may still not desire to have an ordinary switchboard in his private room. It is under these conditions that the Reply-and-Call' System will be found very useful. The central station instrument, as illustrated above, is fitted with automatic replacement levers, by the aid of which the principal, if he desires to speak to any department, has only to take the Hand Combination off the cradle, pull down the lever of the number required, ring, and then speak. After the conversation is finished the act of replacing the Hand Combination automatically restores the lever.
If called up it is only necessary to lift the hand combination, and speak. This instrument is also provided with a pair of through connection plugs enabling the principal to place any two departments in direct communication with each other, and at the same time join in the conversation if he so desires.
A further advantage is that the principal can, if he so wishes, call up, and speak to several departments at one time by simultaneously pressing down the levers of the numbers required.
5, 10, 15, 20, 25 & 30 line models.
For sub stations see B600 & B620.
Last revised: July 07, 2020