Abstract: A trunk interface circuit (105) is disclosed for executing communication and signaling functions associated with telephone calls between subscriber stations of separate telecommunication systems (100, 140). A semiautonomous control circuit (200) is responsive to state signals generated from a central control circuit (120) for establishing the trunk interface circuit (105) in a plurality of states. The semiautonomous control circuit (200) comprises a memory (320) having predetermined data stored therein corresponding to each of the plurality of states. A processor (300) within the semiautonomous control circuit (200) executes certain of the communication and signaling functions as determined by the stored data corresponding to the present state of the trunk interface circuit (105). The communication functions comprise reception of periodic charging pulses from a distant office and subsequent transmittal of signals to the central control circuit (120) representative of the charging pulses.