Abstract: A line switch including a concentrator arrangement for coupling telephone calls between a plurality of subscriber lines and a plurality of port group highways to a central office switching network in a telephony system. The analog voice signals are first digitized and multiplexed into time slot channels on line group highways for transfer to the concentrator arrangement. The concentrator arrangement couples the digitized voice information signals between time slot channels on any of the line group highways and any of the port group highways. The line switch includes control circuitry that selects the time slot channel, line group highway and port group highway to couple the digitized voice information signals between the subscriber line and the central office matrix switch through the concentrator.

Abstract: A method of service code conversion and a service code conversion control circuit are disclosed for translating a dialed service access code in an abbreviated form into the directory number of a line circuit. A class-of-service indication assigned to a calling line circuit and a dialed abbreviated service access code are steered from a common register to a first translation circuit normally providing outgoing routing information for trunk marking. Instead of providing outgoing routing information, the first translation circuit or translator is strapped to recognize the class-of-service indicator and abbreviated dialed access code to enable a service code conversion control circuit. The service code conversion control directs the first translator to perform a conversion of the access code to a type of call indicator and a directory number, both of which are returned to the common register.