AddPac enterprise IP voice door phone solution is to control the visitor access through voice communication using internet line or LAN. AddPac IP voice door phone (AP-AC20, AP-AC50) uses SIP standard protocol based VoIP signaling process function to interwork with AddPac door access control server (AP-ACS1000, AP-ACS1500), IP phones, and soft phone to provide an excellent scalability. Also, it supports the latest voice codec at optimum level like as G.722, G.711, G.729.1, etc. AP-ACS1000 door access control system offers the enterprise level IP voice access solution. Furthermore, AddPac IP voice door phone devices support the analog FXO interface as option. This FXO interface can be enable to voice door phone service via PSTN line using 2-wire cable.