Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems (1921)
Smith, Arthur Bessey, b. 1875, Campbell, Wilson Lee · New York : McGraw-Hill · leaf 241
p the connection desired, whereupon the Boperator will assign an idle trunk in the usual manner. When the Aoperator removes her finger from the order-wire key, the lineswitchrestores to normal position. 220 AUTOMATIC TELEPHONY A B operators position may be made busy to all incoming callswhen… … fi^yt &JIM J3pjQ ox to the trunk. At any time when the B operators of a certain groupare all busy, all the chain relays of that group will be energized, the circuitof the stop relay will be closed and the busy circuit will be closed throughthe primary of the busy induction coil. Since the…
Telephone
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