Bell Telephone Laboratories

Marion Lee Blount

Ronald Joseph Angner

James Volney Lacy

An electronic key telephone line circuit is disclosed for controlling the hold and disconnect conditions with respect to associated telephone stations in response to transient signals generated upon on-hook to off-hook and off-hook to on-hook transitions of those stations. Due to the nature of the switchhook contacts, the tip and ring leads open before the A-lead opens. Since the disconnect condition is determined from a transient signal caused by the tip and ring lead opening together with an A-lead open, and since by its very nature the transient response of the tip and ring lead transition can be finished before the A-lead opens, timing is used to delay the transient signal to insure that the line circuit goes into the proper mode.

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Palo Alto, CA, United States of America

Marion Lee Blount