-
SIP (RFC 3261, 3GPP TS 24.229 Rel-9)
-
3GPP IMS-AKA (RFC 3310, 3GPP TS 33.203, 35.205, 35.206, 35.207, 35.208 and 35.909) with possibilities to activate Early IMS Security (3GPP TS 33.978) for non IMS Registrar
-
Private extension headers for 3GPP
-
Service-Route Discovery (RFC 3608)
-
Proxy-CSCF discovery using DNS NAPTR+SRV
-
SigComp (RFC 3320, 3485, 4077, 4464, 4465, 4896, 5049, 5112 and 1951)
-
NAT Traversal using STUN2 or rport extension
-
Preconditions (RFC 3312, 4032 and 5027) for QoS negociation
-
SMS over IP (3GPP TS 23.038, 24.040, 24.011, 24.341 and 24.451)
-
The E.164 to Uniform Resource Identifiers Mapping (a.k.a ENUM) which allows to directly call telephone numbers (or any SIP mappable address) as per RFC 3761
-
The tel URI for Telephone Numbers (RFC 3966)
-
SIP SIMPLE (Presence Subscription/Publication and Pager Mode IM)
-
Partially implements MMTel (UNI)
-
XCAP (RFC 4825)
-
Session Times (RFC 4028)
-
Audio Codecs: AMR-NB (Both Octet aligned and Bandwidth efficient), GSM, PCMA, PCMU, Speex-NB and iLBC.
-
Video Codecs: H.264 (Base Profile 1.0, 2.0 and 3.0), Theora, H.263, H.263-1998, H.23-2000 and H.261.
-
...and many other features