... features of high integration, easy to build network, seamless interoperability with call agent, strong SIP expansion, high performance/price ratio, ... SIP (IMS compatible), according to RFC2543 and RFC3261, seamless compatible with all popular call agent, including HUAWEI, ZTE, Alcatel-Lucent, etc. Rich ... 1(5.3K/6.3Kbit/s)/G.729, auto-negotiate with call agent. Echo cancellation exceeding ITU-T G.165/ ...