... .1, G.726Echo cancellation: Support G.168, and Hands-free can support 96ms, Hand free Speaker PhoneSupport Voice Gain Setting, VAD, CNGDTMF:Support ... SIP info, DTMF Relay, RFC2833Full duplex hands-free speakerphoneSupport 2 SIP lines. Can connect to SIP1 and SIP2 ...