Base modules contain all necessary interfaces for interconnecting of system components plus interfaces for connecting to subscrib-ers, trunks and communication channels. The base universal module contains 1 up to 4 independent interfaces each of them can be utilized for: output of wideband audio stream to Public Address (PA) zones, conversion of analogue audio signal to digital form and further output to single or several PA zones, SIP end-point registration and signal payload processing, connection to external SIP switches, building up of continuous full duplex subscribers conference.