Terminal Control Elements (TCE) are module control units that control the connection modules in local exchanges
(OVSt). The module control units form the interface between the central switching network, in which the switching functions are implemented, and the connected networks. These module control units take over part of the switching function. They provide the connection to the classical telephone network (POTS), the digital telephone network ISDN, to the central signalling channel (ZZK), to remote maintenance units and other control units.