NATIONAL TELEPHONE COMPANY
BATTERY INTERCOMMUNICATION TELEPHONES
AUTOMATIC INTERCOMMUNICATION WALL AND TABLE SET WITH LINE SELECTOR
Pattern No. B550
Comprises - Hand Combination Transmitter and Receiver, Cord, Automatic Cradle-switch, Induction Coil, Push Button, Line Selector with Concealed Contacts and Patent Automatic Disconnecting Device.
The B550 Wall Set is fitted a Bell and the B555 Table Set with a Buzzer, in addition to which, the Table Set is complete with a Wall Rosette and Cord.
5, 10, 15, 20, 25 & 30 line models.
With these Sets it is not necessary to move the Selector except when selecting a line, and calls may he received and answered irrespective of its position.
After conversation the act of replacing the Hand Combination automatically disconnects the switch. Cross ringing cannot occur under any conditions.
Last revised: July 07, 2020