NATIONAL TELEPHONE COMPANY
B560

BATTERY INTERCOMMUNICATION TELEPHONES

SECRET SERVICE

WALL SET

Pattern No. B560

Comprises - Hand Combination Transmitter and Receiver, Cord, Bell, Relay, Automatic Switch-hook, Line Selector, Ringing Key and Induction Coil.

Produced in 5, 10, 15 & 20 line models.

The most important point in connection with this system lies in the fact that only single wiring is required in the installation. The instruments give absolute secrecy and freedom from interruption.  A third party cannot accidentally, or designedly, overhear a conversation.  The line selector can be left in any position after using.


 
 
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Last revised: November 17, 2025

FM2