BATTERY INTERCOMMUNICATION TELEPHONES
Pattern No. B560
Comprises Hand Combination Transmitter and Receiver, Cord, Bell, Relay, Automatic Switch-hook, Line Selector, Ringing Key, and Induction Coil.
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.