Digital communication is a reliable way to communicate, the advantages are less sensitivity to changes in environmental conditions (temperature, etc.), Easy multiplexing, Easy signaling, Hook status, address digits, call progress information, Voice and data integration, Easy processing like encryption and compression, Easy system performance monitoring, QOS monitoring, Integration of transmission and switching, Signal regeneration, operation at low SNR, superior performance.
A small capacity digital PBX-key system which uses a single processor to control the system. Since only a single processor is employed, the system is interrupt controlled. In the system, there is a codec per line, the codec each having sufficient programmability to eliminate the need for time slot interchangers.