The PBX means private branch exchange is telephony system which switches calls between enterprise users on the local lines. The purpose of the PBX/EPBX is to save the cost of requiring a line for each user in a company.
The CUCM or cisco unified communication manager is a IP- based voice, video,messaging,voice mail enable software based application which provide various integration facilities to integrate various telephony applications.However, CUCM works on IP based signalling(SIP) and PBX works on analog based signalling.
Voice,Video & Data Technology 