SIP protocol
RFC3261
RFC3262
RFC3264
RFC3311
RFC3515
RFC3581
RFC3966
RFC4028
SIP registration (Per trunk, per gateway)
Registration expire setting
SIP trunk
Backup SIP proxy (Up to 10 proxies)
Peer-to-peer communication
SIP-to-SIP relay
Hook flash relay (INFO)

FXS
Polarity inverse generation
Caller ID generation (FSK, DTMF, before ring and after ring)
Ring cadence setting
Ring frequency setting
Volume control
Hook flash timing setting
Message waiting indicator (FSK, polarity inverse)

FXO
Polarity inverse detection
Caller ID detection (FSK, DTMF, before ring and after ring)
Busy tone detection
DTMF out-pulsing timing setting
Volume control
Ring timing setting
Automatic attendant (2nd ? stage dialing)
Direct inward dialing
Busyout

Codec/FAX/RTP
G.711ALaw, G.711ULaw, G.729A, G.723.1r63, G.723.1r53, GSM
T.38 fax relay, T.30 fax transparent
Echo cancellation
Dynamic jitter buffer management
Static jitter buffer
DTMF relay (RFC 2833, SIP/INFO, inband)

Voice QoS
IEEE 802.1p tag
DiffServ code point (TOS) bits

Call control
Blind transfer
Explicit transfer
Call forward on busy
Call forward on no answer
Call forward variable
Call waiting
Caller ID
Caller ID blocking
Caller ID on call waiting
Distinctive ring
Do not disturb
Music on hold
Color ring back tone
Call progress tone (Configurable)
Release control (Called party control, calling party control)
Three-way calling
Speed dialing
Calling and called number based routing
Call number transformation (Add, delete, replace)
Hunt group (Sequential and circular hunt)
Ring group
Digit map
PSTN failover (Upon IP network break or failure to reach SIP proxy, or power break)

Networking
DHCP
DNS/DDNS
PPPoE
NAT traversal (STUN)

Security
IP access list (IP table)
SIP/RTP/TELNET/HTTP/TFTP port assignment
Web-utility access privilege (Admin and user)

System management
TR069-based management (Include TR069, TR104, and TR106)
Standard SNMP agent (MIB v2)
Web-based management interface (Local and remote access)
Firmware upgrade
Log management (8 levels)
Syslog
Various debugging and call trace
TCP dump
Remote management with console and telnet
Configuration files import and export
System status monitoring and statistics