RFC Support
The SIP Trunking service supports the following RFC’s. Full compliance is subject to differences in interpretation, interoperability constraints and the exceptions noted below.
Table 8 -- SIP Trunking reference RFCs and other Standards
RFC
Supported
RFC 2327 Session Description Protocol
Yes
RFC2543 SIP: Session Initiation Protocol
Yes, Putting Media streams on Hold, Indicate the IP in SDP message when "call-hold" mechanism is used according RFC 2543: Gamma will support receiving either the actual IP or 0.0.0.0 if interworking to TDM.
If the incoming/outgoing route is via a SIP interconnect partner this may not be the case.
RFC 2833 - RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals
Yes
SIP RFC 3261- SIP Messages, Headers & Protocol
Yes
RFC 3262 - Reliability of Provisional Responses in SIP:
Yes
RFC 3264 - An offer/answer model with SDP:
Yes
SIP RFC 3311 - SIP Update Method
Yes (only during unconfirmed dialogue). Re-INVITE should be used when dialogue is in confirmed state.
SIP RFC 3325 - Privacy extensions to SIP for Asserted Identity within trusted networks
Yes
SIP RFC 3326 - Reason-Header Field for SIP
Yes
RFC 3398 - ISDN to SIP Mapping:
Yes
RFC 3551 - RTP Profile for audio:
Partial, Gamma will only support G711, G729 and G729A codecs
RFC 4028 Session Timers in the Session Initiation Protocol
Yes
NICC ND1017:2006/07. TSG/SPEC/017. Interworking between Session Initiation Protocol (SIP) and UK ISDN User Part (UK ISUP)
Yes