... voice functions are provided by the built-in PBX, SIP server, and SIP access gateway ● Value-added voice services include multi ... routers at the headquarters office as an IP PBX and SIP voice gateway.IP PBX applicationTo improve communication efficiency, all AR-Series ... NAT, and sub-interface managementVoiceRTP, SIP, SIP AG, IP PBX/TDM PBX, FXO/FXS, VoIP/conference call, BEST, DISA, and SBC3GCDMA 2,000 ...