IP Office is a converged telephony system that combines aspects of a traditional PABX telephone system and IP data and telephony systems. The Branch solution supports VoIP that includes IP trunks, SIP 9600 series telephones for centralized users, as well as H.323 and SIP IP telephones for local IP Office users. In a Distributed, Mixed, or Centralized environment connected to the Avaya Aura® infrastructure, the VoIP connection is established between the IP Office branch and the enterprise center over WAN. VoIP signaling is based on SIP signaling between the IP Office in the branch and the Avaya Aura® Session Manager in the enterprise center.