Excelltel cs+424 24-line intercom pabx system. Compatible with KTS and SLT, plug and play, caller ID transferred, auto fax detect, automatically IP code access, extension password, line access mode selection, line duration time limit, day / night service, 7 multiple channel communication, monitor voice record, outside caller call extension by one touch, auto / manual dial-out mode, PC call management and bill software support, speed dialing, external music on hold socket