Port multiplexer for telephone signal processing systems

Abstract

A link is connected between each linefinder/first selector combination of a telephone system. The links, in turn, are selectively connected to a group of ports, several links to one port, and the ports are connected to one or more telephone signal processors. When a telephone goes OFF HOOK, the sleeve or C lead of the linefinder at which that telephone's scanning switch is then pointing (determined by the associated link being connected to an available port) is grounded. When the address of this link next occurs in a time multiplex cycle, the link is latched, and the telephone's tip and ring leads are connected to the link's port. After signal processing has ended, or some other release action occurs, the port generates a release signal that disconnects the link from the port. While any link is connected to its associated port, a make-busy ground circuit forming part of eack link applies a false busy signal to the linefinders associated with the other links common to the same port. The false busy signals prevent the linefinders associated with the other links from attempting to seize the busy port via those links. Termination of a conversation flowing through one link creates a WINK signal that causes a release of its associated linefinder, even though another link may be connected to the associated port at the time the conversation is terminated. In the case where two links associated with the same port attempt to seize that port at substantially the same time, the link having the earlier address in the time multiplex cycle actually seizes the port. The second link, upon sensing the creation of a false busy signal (causes by the seizing of the port by the first link) is dumped. Dumping the second link causes the dumped link's linefinder scanning switch to route the second call to a linefinder having a link whose associated port is available for signal processing.