SIP IP PABX Phone system with 4 to 96 FXS/FXO ports SIP trunks for least cost calls 120 IP users Billing, ... group, Auto-Attendant, 3-way-conference;Embedded SoHo IP PBX phone system with 4,8 or 16 FXO analog ports, ... and 8,16,24 FXS local extensions; and 60 IP ... The RT20 is an All-in-One converged communication system for small and mid-size offices, home offices ...