Call control protocol: SIP(RFC-3261) or H.323 V4 or MGCP.   Echo cancellation: G.165/G.167 16ms. IP Address: PPPoE, DHCP client, Static IP.  LCD Display: Dialed Number, Coin Value, Remaining Credit, Reminding Message, Self-Diagnostic Message, and Revenue Information.   Function Keys: Voice Amplification, Language Choice, Redial, Follow-on-Call.