Abstract: A PCM telephone switch that is simultaneously compatible with both DS-1 and CEPT PCM formats is disclosed. A switch module performs timeslot switching of individual subchannels between DS-1 and CEPT trunks which are input by way of digital group interfaces. Each group interface couples to one or more trunks of serial bit streams of either DS-1 or CEPT format standards. After the input serial bit stream is converted to a parallel format, it is used as eight bits of the address bits of data processing ROMs from which a corresponding 8-bit word is parallel read on a per channel basis and routed to the appropriate output data processing ROMs. The output data bits of the ROMs are the processed data bits which are reconverted to serial format for either DS-1 or CEPT standards as required by the output trunk. A-law or .mu.-law decoding and encoding is accomplished independently from input to output channel on a per channel basis.

Abstract: A digital radiotelephone exchange having self diagnostic individual subchannel loopback is disclosed. An individual subchannel of an outbound PCM data stream is substituted for an individual subchannel of an inbound PCM data stream. The removed individual subchannel of the inbound PCM data stream is either substituted in the outbound PCM data stream or discarded. Line signal bits may be generated and substituted for the line signal bits of the individual subchannel in the outbound PCM data stream.