Subscriber line-trunk circuit

Abstract From the Canadian patent

R. Treiber -1, SUBSCRIBER LINE TRUNK/CIRCUIT Abstract of the Disclosure, A microprocessor controlled subscriber line circuit for interfacing analog telephone lines and trunks to a digital switching system is disclosed. All processing of incoming analog signals is accomplished by the line circuit including, the interface between the line and a digital switching matrix measuring, monitoring, testing of the signals associated with the speech path, generating talking battery ringing and other, tones, equalization and providing the two-wire to four-wire conversion with acceptable echo performance and minimized cross-office transmission loss. The analog-to-digital and digital-to-analog …