... meet customer’s requirements:Supporting many applications such as call forwarding, caller ID, DND, busy tone, conference ... supports SIP 1.0/2.0.Main featuresSupport Call forwarding, Call waiting, Call display etc standard voice service and Busy tone ... ModeTelephony FeaturesCaller ID display or block, Call waiting, Blind or attended call transfer, Call forward, Do not disturbQosDiff Serve, TOS ...