SIP IP PABX Phone system with 4 to 96 FXS/FXO ports ... Auto-Attendant, 3-way-conference;Embedded SoHo IP PBX phone system with 4,8 or 16 FXO analog ports, and ... The RT20 is an All-in-One converged communication system for small and mid-size offices, home offices ... 60 60RT20-20S/4 20 4 60 60 System Features Built-in SIP Server SIP Trunk Auto ... Detection Automatic Route Selection VoIP IPPBX SIP Phone System