NATIONAL TELEPHONE COMPANY
B80

WALL AND TABLE SET

Pattern No. B80

Comprises - Granular Carbon Transmitter and Receiver, Cord, Automatic Switch-hook, Induction Coil, Bell, and Wall Rosette.

This instrument is arranged for double line Intercommunication System and by special means absolute secrecy is ensured.  It is impossible to tap the lines and it is also impossible to overhear by induction if properly twisted metallics are used.

Some or the chief advantages, therefore, are as follows:-
The simple insertion of the plug selects the line and calls at the same time.
A distinct method of ascertaining whether the person wanted is engaged or available.
If the person wanted is engaged, a means is provided whereby the person calling receives a distinct signal directly the person required is disengage.
After having carried on a conversation if the caller omits to withdraw his plug he receives a signal which reminds him of the omission.
The impossibility of any person not required tapping the line on which a conversation is taking place.

The illustration shows the instrument arranged as a Table Set with the bell on the back.  If required as a wall Set. the bell can be removed from the back and fixed on the bottom.  The fixing screws establish the connection with the rest of the apparatus.

5, 10, 15, 20, 25 & 30 line models.

Taken from the 1903 Catalogue. 

Last revised: July 07, 2020