BATTERY INTERCOMMUNICATION TELEPHONES
Pattern No. B580
Comprises Hand Combination Transmitter and Receiver, fitted with Ringing and Speaking Key, Cord, Bell, and Line Selector.
An advantage in connection with these Sets is that a common battery of three or four cells provides the current required for both ringing and speaking.
The terminals are so arranged that the connections may be made on either back or front.
5 & 10 line models.