In this paper, the authors describe IP-PBX server for small business organization based on asterisk one of the first open source PBX software package. The traditional EPABX system can be replaced by Internet Protocol-Private Branch eXchange (IP-PBX) which uses intranet as backbone as each organization has existing local area network. IP-PBX is cost efficient and uses only one computer as a server having Linux based operating system called "CentOS". The clients are connected to server using hard/soft phones. Communication in the range of Wi-Fi is also possible.