... IVR, Recording All-in-One SIP IP PABX for SOHO useressupport 4 to 96 analog ports (extensions ... working under NAT for remote IP users by DDNSRecording, Voice mail,Music on Hold,Ring group, Auto-Attendant ... is an All-in-One converged communication system for small and mid-size offices, home offices ... built-in IVR, calls records, and downloads for color ring back tones.Application Digram: RT20 Series IP ...