Abstract: A call denial circuit for use in a key telephone system is arranged to operate in response to a communication line reversal from the central office to create a timed interval during which the A leads from the associated key stations are observed. If any station having unrestricted capability is off-hook and active during the timed interval, the call denial circuit is inhibited and the call proceeds in the normal manner. At the expiration of the timed interval the call may continue even though only restricted stations remain on the established connection. The circuit is arranged so that a station may have some lines which are restricted and some lines which are unrestricted.
Type:
Grant
Filed:
March 27, 1975
Date of Patent:
June 29, 1976
Assignee:
Bell Telephone Laboratories, Incorporated