VoIP
SIP (SIP RFC3261,RFC 2543)/IAX2 support.
2 SIP lines + 1 IAX2 line
Redundancy sip server capable.
Hotline.
Call Forward、Call transfer、Call hold、Call waiting, 
3-way Talking、Pickup、Join call、Redial、Unredial、
Call Park、vport、click to dial
DND(Do Not Disturb),
Black List,Limit List
E.164 dial plan and customized dial rules

Voice
Tone generation and Local DTMF re-generation according with ITU-T
G.711(A-law or u-law) , G722 , G723 G729
AGC(Auto Gain Control)
AEC(Auto Echo Cancellation)
VAD (Voice Activity Detection)
CNG(Comfort Noise Generation
G.165 compliant 96 ms echo cancellation

Networking
Static/Dynamic WAN-IP-Addressing
NAT, Firewall.
Support VPN (L2TP) Open VPN
Support DMZ
WAN support Primary and Alter function
Qos support Diffserv
Support VLAN
DHCP client and server.
Support PPPoE, (used for ADSL, cable modem connecting).

Protocols
MAC Address
TCP:Transmission Control Protocol 
DHCP:Dynamic Host Configuration Protocol
PPPoE:PPP Protocol over Ethernet
PoE(option)
SNTP, Simple Network Time Protocol
STUN - Simple Traversal of User Datagram ...
MD5 Message-Digest Algorithm
DNS: Domain Name Server
RTP: Real-time Transport Protocol
RTCP:Real-time Control Protocol
Telnet:Internet's remote login protocol
HTTP:Hyper Text Transfer protocol
FTP:File Transfer protocol
TFTP:Trivial File Transfer Protocol

Management
Web, telnet and keypad management.
Adjustable user password and super password
Upgrade firmware through HTTP, FTP or TFTP.
Telnet remote management.
Upload/download configration file
Auto-provisioning ( firmware and configuration) 
Safe mode provide reliability
Phone book, maximum 500 entries.