1. Protocols, NAT Traversal
SIP(RFC3261) STUN Codec Voice Quality G. 711 u-Law G. 711 a -Law G. 723.1 (5.3k/6.3k) G. 729(A/AB) G. 726(16k/24k/32k/40k) GSM VAD CNG AEC, LEC Packet Loss Compensation Jitter Buffer

2. Telephone Function, Call Function
Normal PSTN phone(No battery support) PSTN Phone VoIP Phone Volume Adjustment Speed dial key Phone book Redial Flash Speaker Phone 3-Way Conference Hot line Call Hold Call Waiting Call Forward Call Waiting Call Mute Caller ID(FSK/DTMF)

3. Tone, DTMF Function
Ring Tone Ring Back Tone Dial Tone Busy Tone User Programming Tone DTMF Detection DTMF Generation In-band DTMF Out-of-band DTMF(RFC2833)? SIP Info

4. FAX Function, Dial Methods
T. 38 Direct IP Call w/o SIP Proxy Dial number via SIP server

5. Configuration, Firmware Upgrade
Web browser Console/Telnet/Keypad Auto-Configuration TFTP Console HTTP Auto-Provision

6. TCP/IP, IP Assignment
IP/TCP/UDP/RTP/RTCP/ICMP/ARP/ RARP/SNTP TFTP/PPPoE Client DHCP/DNS Client Telnet/HTTP Server IEEE802.1 P/Q Tos/Diffserv NAT/DHCP Server Static IP DHCP