A PBX (private branch exchange) is a telephone system within an enterprise that switches calls between enterprise users on local lines while allowing all users to share a certain number of external phone lines. Users of the PBX phone system share a number of outside lines for making external phone calls. A PBX connects the internal telephones within a business and also connects them to the public switched telephone network (PSTN), VoIP Providers and SIP Trunks. EPABX system is an impressive business solution to meet the office needs of internal communication. It provides a business phone system that enables switching internal calls between two or more persons on different extensions on the same business phone connection.