NATIONAL TELEPHONE COMPANY
BATTERY INTERCOMMUNICATION TELEPHONES
Pattern No. B500
Comprises - Hand Combination Transmitter and Receiver with Double Contact Key, Cord, Fixed Hook, Induction Coil, Bell, Two Push Buttons, and Line Selector and in the case of the Table Set, a Wall Rosette and Cord.
These instruments are fitted with a ringing button, and a second button, by means of which when any two stations each put over their Selector Switches to the otherís number, and then each press the second button, the common return is cut out, and the line between the two stations becomes a metallic circuit only, thus minimising any cross talk due to induction, and making the conversation more private.
10, 15 & 20 line models.
Was B70 in the 1903 Catalogue.
Last revised: July 07, 2020