Time division multiplex (tdm) switching system especially for pulse code

Abstract

A TDM switching system for providing selected connections between large numbers of lines and trunks and which may combine, in an integrated system, several TDM switching systems which are adapted to handle smaller numbers of lines and trunks so as to expand the capacity of such smaller TDM systems. The system has a distributed, modular architecture in which the lines and trunks are arranged in a plurality of domains. The domains each have a link controller which links the domains to interdomain PCM highways. The domains each include, as the members thereof, a plurality of devices. These member devices can be port interfaces which connect telephone lines and trunks and convert the analog telephony signals into PCM signals and vice versa, circuits which provide services, telephony processors which contain the data base of the addresses (telephone numbers) of the various lines and trunks, ringing generators, and interface devices which provide a gateway for signals into the domains for the smaller TDM switching systems. Each domain has its own intradomain PCM highway to which the devices are connected and device control links connecting the devices to a link controller and carrying signalling messages. Each domain may have a different complement of devices. Control signals control the telephony signal process along separate links, unique to each device, which connect that device to the link controller.