... (ITU-T Q.931,Q.921) -V5.2(ITU-T G.964, G.965)·VoIP protocol support: -SIP(RFC3261, RFC3362(T.38 ... (DTMF)); -Code: G.711µ-Law and A-Law, G.711 Appendix 1,G.723.1 and G.723.1 Annex A, G.729 Annex A ... and Annex B,G.726;·Echo ... Cancellation: G.168 128 ...