公开(公告)号：US3591725A

公开(公告)日：1971-07-06

申请号：US3591725D

申请日：1969-07-11

Applicant: BELL TELEPHONE LABOR INC

Inventor： MORSE CHARLES E ,  SMITH JOHN P ,  TRUBY RALPH

IPC: H04M9/00 ,  H04Q3/00 ,  H04M3/42

CPC classification number: H04Q3/0012 ,  H04M9/005

Abstract: A key telephone system is arranged to provide access for any number of key telephone stations to any number of line circuits. When two or more stations are selectively connected to the same line circuit, the transmission capability of each such station is placed under control of a push-to-talk key at that station. The line circuit is associated with a selector for scanning each such connected station sequentially and for providing exclusive transmission capability to a first detected station having an operated push-to-talk key. On simultaneous connections to certain line circuits, the enabling of an override key at any of the connected stations provides unlimited transmission capability from that station without regard to the operational status of the push-to-talk key.