ATM TELEPHONE T.720

 
"THE PHANTOPHONE"

For simultaneous telephony on telegraph and block signalling circuits.

As the T714A except for it is arranged for Magneto calling.

This is achieved by means of an earthed telegraph circuit to a metallic loop telephone circuit.

Taken from the ATM catalogue Telegraph Apparatus and Accessories No. 59 (Jan 1921)

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Last revised: February 18, 2026

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