Title: Telephone station make-busy circuit

Abstract: A telephone central office trunk utilized for establishing connections of calling telephone station lines with a called telephone station line is arranged to enable a subscriber to make a called telephone station appear busy to incoming calls. The trunk is provided with apparatus arranged to respond to the momentary appearance of a low impedance across the called telephone station line in response to ringing signals applied thereto by opening the established connections and applying busy tone to the calling telephone station lines.

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Inventors: Catterall, John Mason (Columbus, OH, US)

Application Number: 616284
Filing Date: 1975-09-24
Publication_date: 1976-12-14
Assignee: Bell Telephone Laboratories, Incorporated (Murray Hill, NJ)
Primary Class(es): 379/257 379/381, 379/387.01
Other Classes:
US Patent Ref:

3673339	Jun, 1972	Korn	179/18.
3777067	Dec, 1971	Kilby	179/84.

Other Refs:
Primary Examiner: Cooper, William C.
Assistant Examiner:
Attorney: Marshall; Dwight A.