The TCM8002 provides the data transceiving, data processing, and SAT (supervisory audio tone) functions for the AMPS (advanced mobile phone service) and TACS (total access communications system) cellular telephone standards. A highly integrated device, the TCM8002 includes a number of additional functions that are helpful in the implementation of the typical cellular telephone. These extra functions include a watchdog timer, which is normally external to the telephone microcontroller, and two 8-bit- and one 4-bit-wide user-programmable general-purpose input/output ports. These can be used to provide port expansion for the microcontroller. An 8-bit counter/timer for user-defined purposes is also included. To facilitate the application of the TCM8002 and to minimize the number of connections, a single serial interface to the microcontroller is used for controlling, receiving, and transmitting data. There is also a dedicated interface, including a compatible clock signal, to the companion TCM8010 audio processor that performs most of the audio processing required in a cellular telephone. Additional outputs are also provided for interfacing to other audio processors.