Support SIP2.0 (RFC3261), TCP/UDP/IP, RTP/RTCP/, HTTP, ICMP ARP/RARP, DNS, DHCP, NTP, PPPoE, STUN, and TFTP etc; Inside Router/NAT, gateway, and DMZ Port transmit; Support the PSTN making or receiving calls (by the FXO Port); Use the DSP CNOS chip to keeping a wonderful audio-quality, Jitter control adn packet loss concealment technology; Support kinds of voice coding, including G.711 (alaw and u-law), G.723.1 (5.3k/6.3k), G.726 (40K/32K/24K/16K/), G.729A/B, and iLBC; Support incoming call on show, restricting, and holding, Calling router automatically(PSTN TO VOIP ,VOIP TO PSTN). disconnection, call transfer, call divert, DTMF, dialing project, etc; Support conference call; Support passing through and T38 fax; Support layer 2 (802.1Q VLAN, 802.1p) and layer 3 (QoS, DiffServ, ToS); Support NAT auto- penetrating, no need to modify the ting of the NAT; Support configuration files by inside IVR equipment, Web browser, or TFTP and HTTP Center Server; Support upgrading encrypts configuration files by TFTP or HTTP; Microminiaturize and legerity design (size as a wallet), a adapter that convenient for schlepping. Double modes in busy signal testing intelligently. Remote .