voice features support dns register; support h.323 v4, mgcp and sip protocol; support dhcp automatic allocation of ip address and other parameters; support a variety of nat passing and firewall passing; meet itu-t standard as well as generation and test of dtmf; support g.711a/u,g.723.1 5.3/6.3 and g.729/a/b/ab/gsm610 algorithm of voice coding and decoding; support voice activity detection (vad), comfort noise generation (chk), acoustic echo; cancellation (aec) and dynamic voice technology. its sound can match with traditional telephone. support pppoe protocol (when used on adsl and cable modem connection). support many net structures, such as lan, city wide band, special line net, xdsl of telecom, modem, wide band and cable modem wide band net .......