Two steel plates from private automatic branch exchange
Two steel plates from, Private automatic branch exchange made by Relay Automatic Telephone Co., c.1923
Private automatic branch exchange made by Relay Automatic Telephone Co., c.1923
Two steel plates from, Private automatic branch exchange made by Relay Automatic Telephone Co., c.1923
Relay onto branch exchange from, Private automatic branch exchange made by Relay Automatic Telephone Co., c.1923