RFC number	Short description	Support status
RFC 2327	SDP: Session Description Protocol	Obsoleted by RFC 4566
RFC 2833	URLs for Telephone Calls [tel]	Obsoleted by RFC 3966
RFC 2833	RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals [DTMF]	Obsoleted by RFC 4733 RFC 4734
RFC 2976	The SIP INFO Method	Obsoleted by RFC 6086
RFC 3204	MIME media type ISUP	Passthrough
RFC 3261	Session Initiation Protocol	Supported
RFC 3262	Reliability of Provisional Responses [PRACK]	Supported
RFC 3265	Session Initiation Protocol (SIP)-Specific Event Notification [NOTIFY]	Obsoleted by RFC 6665
RFC 3311	The Session Initiation Protocol (SIP) UPDATE Method	Supported
RFC 3323	A Privacy Mechanism for the Session Initiation Protocol (SIP)	Supported
RFC 3324	Short Term Requirements for Network Asserted Identity	Supported
RFC 3325	Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity within Trusted Networks	Supported
RFC 3326	The Reason Header Field for the Session Initiation Protocol (SIP)	Supported
RFC 3398	Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping	Unsupported
RFC 3428	Session Initiation Protocol (SIP) Extension for Instant Messaging [MESSAGE]	Unsupported
RFC 3515	The Session Initiation Protocol (SIP) Refer Method	Unsupported
RFC 3605	Real Time Control Protocol (RTCP) attribute in Session Description Protocol (SDP)	Supported
RFC 3702	Authentication, Authorization, and Accounting Requirements for the Session Initiation Protocol (SIP) [RADIUS]	Unsupported
RFC 3711	The Secure Real-time Transport Protocol (SRTP)	Unsupported
RFC 3824	Using E.164 numbers with the Session Initiation Protocol (SIP) [ENUM/NAPTR]	Unsupported
RFC 3840	Indicating User Agent Capabilities in the Session Initiation Protocol (SIP)	Unsupported
RFC 3903	Session Initiation Protocol (SIP) Extension for Event State Publication [PUBLISH]	Unsupported
RFC 3966	The tel URI for Telephone Numbers	Supported
RFC 4028	Session Timers in the Session Initiation Protocol (SIP)	Unsupported
RFC 4566	SDP: Session Description Protocol	Obsoleted by RFC 8866
RFC 4733	RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals [DTMF]	Passthrough
RFC 4734	Definition of Events for Modem, Fax, and Text Telephony Signals [DTMF]	Passthrough
RFC 5079	Rejecting Anonymous Requests in the Session Initiation Protocol	Supported
RFC 5365	Multiple-Recipient MESSAGE Requests in the Session Initiation Protocol (SIP) [MESSAGE]	Unsupported
RFC 5806	Diversion Indication in SIP	Supported
RFC 6086	Session Initiation Protocol INFO Method and Package Framework	Supported
RFC 6337	Session Initiation Protocol Usage of the Offer/Answer Model	Supported
RFC 6665	SIP-Specific Event Notification [NOTIFY]	Supported
RFC 8224	Authenticated Identity Management in the Session Initiation Protocol [Stir-Shaken]	Supported
RFC 8225	PASSporT: Personal Assertion Token [Stir-Shaken]	Supported
RFC 8226	Secure Telephone Identity Credentials: Certificates [Stir-Shaken]	Supported
RFC 8588	Personal Assertion Token (PaSSporT) Extension for Signature-based Handling of Asserted information using toKENs (SHAKEN) [Stir-Shaken]	Supported
RFC 8866	SDP: Session Description Protocol	Supported