Session Initiation Protocol (SIP) Parameters (last updated 2008-02-07) Registries included below: - Header Fields - Option Tags - Warning Codes (warn-codes) - Methods and Response Codes - Reason Protocols - Security Mechanism Names - Compression Schemes - SIP/SIPS URI Parameters - Header Field Parameters and Parameter Values - URI purposes - Identity-Info Parameters - Identity-Info Algorithm Parameter Values For registration procedures, please see [RFC3427] Registry Name: Header Fields Reference: [RFC3261] Section 27.3 Note: The table below lists the header fields currently defined for the Session Initiation Protocol (SIP) [RFC3261]. Some headers have single-letter compact forms (Section 7.3 of RFC 3261). Header field names are case-insensitive. Registry: Header Name compact Reference ----------------- ------- --------- Accept [RFC3261] Accept-Contact a [RFC3841] Accept-Encoding [RFC3261] Accept-Language [RFC3261] Accept-Resource-Priority [RFC4412] Alert-Info [RFC3261] Allow [RFC3261] Allow-Events u [RFC3265] Authentication-Info [RFC3261] Authorization [RFC3261] Call-ID i [RFC3261] Call-Info [RFC3261] Contact m [RFC3261] Content-Disposition [RFC3261] Content-Encoding e [RFC3261] Content-Language [RFC3261] Content-Length l [RFC3261] Content-Type c [RFC3261] CSeq [RFC3261] Date [RFC3261] Encryption (Deprecated) [RFC3261] Error-Info [RFC3261] Event o [RFC3265] Expires [RFC3261] From f [RFC3261] Hide [RFC3261] (deprecated) History-Info [RFC4244] Identity y [RFC4474] Identity-Info n [RFC4474] In-Reply-To [RFC3261] Join [RFC3911] Max-Forwards [RFC3261] MIME-Version [RFC3261] Min-Expires [RFC3261] Min-SE [RFC4028] Organization [RFC3261] P-Access-Network-Info [RFC3455] P-Answer-State [RFC4964] P-Asserted-Identity [RFC3325] P-Associated-URI [RFC3455] P-Called-Party-ID [RFC3455] P-Charging-Function-Addresses [RFC3455] P-Charging-Vector [RFC3455] P-DCS-Trace-Party-ID [RFC3603] P-DCS-OSPS [RFC3603] P-DCS-Billing-Info [RFC3603] P-DCS-LAES [RFC3603] P-DCS-Redirect [RFC3603] P-Early-Media [RFC5009] P-Media-Authorization [RFC3313] P-Preferred-Identity [RFC3325] P-Profile-Key [RFC5002] P-User-Database [RFC4457] P-Visited-Network-ID [RFC3455] Path [RFC3327] Permission-Missing [RFC-ietf-sip-consent-framework-04.txt] Priority [RFC3261] Privacy [RFC3323] Proxy-Authenticate [RFC3261] Proxy-Authorization [RFC3261] Proxy-Require [RFC3261] RAck [RFC3262] Reason [RFC3326] Record-Route [RFC3261] Refer-Sub [RFC4488] Refer-To r [RFC3515] Referred-By b [RFC3892] Reject-Contact j [RFC3841] Replaces [RFC3891] Reply-To [RFC3261] Request-Disposition d [RFC3841] Require [RFC3261] Resource-Priority [RFC4412] Response-Key (Deprecated) [RFC3261] Retry-After [RFC3261] Route [RFC3261] RSeq [RFC3262] Security-Client [RFC3329] Security-Server [RFC3329] Security-Verify [RFC3329] Server [RFC3261] Service-Route [RFC3608] Session-Expires x [RFC4028] SIP-ETag [RFC3903] SIP-If-Match [RFC3903] Subject s [RFC3261] Subscription-State [RFC3265] Supported k [RFC3261] Target-Dialog [RFC4538] Timestamp [RFC3261] To t [RFC3261] Trigger-Consent [RFC-ietf-sip-consent-framework-04.txt] Unsupported [RFC3261] User-Agent [RFC3261] Via v [RFC3261] Warning [RFC3261] WWW-Authenticate [RFC3261] Registry Name: Reason Protocols Reference: [RFC3326] Registry: Protocol value Protocol Cause Reference -------------- ------------------------------ --------- SIP Status code [RFC3261] Q.850 Cause value in decimal [ITU-T Q.850] representation Preemption Cause value in decimal* [RFC4411] * see the separate "Preemption" Registry for default reason-text strings http://www.iana.org/assignments/preemption-namespace Registry Name: Option Tags Reference: [RFC3261] Section 27.1 Note: Option tags are used in header fields such as Require, Supported, Proxy-Require, and Unsupported in support of SIP compatibility mechanisms for extensions. The option tag itself is a string that is associated with a particular SIP option (that is, an extension). It identifies the option to SIP endpoints. Registry: Name Description Reference ----------- ------------------------------------------ --------- 100rel This option tag is for reliability of [RFC3262] provisional responses. When present in a Supported header, it indicates that the UA can send or receive reliable provisional responses. When present in a Require header in a request it indicates that the UAS MUST send all provisional responses reliably. When present in a Require header in a reliable provisional response, it indicates that the response is to be sent reliably. early-session A UA adding the early-session option tag [RFC3959] to a message indicates that it understands the early-session content disposition. eventlist Extension to allow subscriptions to lists [RFC4662] of resources from-change This option tag is used to indicate that [RFC4916] a UA supports changes to URIs in From and To header fields during a dialog. gruu This option tag is used to identify the Globally [RFC-ietf-sip-gruu-15.txt] Routable User Agent URI (GRUU) extension. When used in a Supported header, it indicates that a User Agent understands the extension. When used in a Require header field of a REGISTER request, it indicates that the registrar is not expected to process the registration unless it supports the GRUU extension. histinfo When used with the Supported header, [RFC4244] this option tag indicates support for the History Information to be captured for requests and returned in subsequent responses. This tag is not used in a Proxy-Require or Require header field since support of History-Info is optional. join Support for the SIP Join Header [RFC3911] norefersub This option tag specifies a User Agent [RFC4488] ability of accepting a REFER request without establishing an implicit subscription (compared to the default case defined in RFC3515). path A SIP UA that supports the Path extension [RFC3327] header field includes this option tag as a header field value in a Supported header field in all requests generated by that UA. Intermediate proxies may use the presence of this option tag in a REGISTER request to determine whether to offer Path service for for that request. If an intermediate proxy requires that the registrar support Path for a request, then it includes this option tag as a header field value in a Requires header field in that request. precondition An offerer MUST include this tag in the [RFC3312] Require header field if the offer contains one or more "mandatory" strength-tags. If all the strength-tags in the description are "optional" or "none" the offerer MUST include this tag either in a Supported header field or in a Require header field. pref This option tag is used to ensure that a [RFC3840] server understands the callee capabilities parameters used in the request. privacy This option tag indicates support for the [RFC3323] Privacy mechanism. When used in the Proxy-Require header, it indicates that proxy servers do not forward the request unless they can provide the requested privacy service. This tag is not used in the Require or Supported headers. Proxies remove this option tag before forwarding the request if the desired privacy function has been performed. replaces This option tag indicates support for the [RFC3891] SIP Replaces header. resource-priority Indicates or requests support for the [RFC4412] resource priority mechanism. sdp-anat The option-tag sdp-anat is defined for use [RFC4092] in the Require and Supported SIP [RFC3261] header fields. SIP user agents that place this option-tag in a Supported header field understand the ANAT semantics as defined in [RFC4091]. sec-agree This option tag indicates support for the [RFC3329] Security Agreement mechanism. When used in the Require, or Proxy-Require headers, it indicates that proxy servers are required to use the Security Agreement mechanism. When used in the Supported header, it indicates that the User Agent Client supports the Security Agreement mechanism. When used in the Require header in the 494 (Security Agreement Required) or 421 (Extension Required) responses, it indicates that the User Agent Client must use the Security Agreement Mechanism. tdialog This option tag is used to identify the target [RFC4538] dialog header field extension. When used in a Require header field, it implies that the recipient needs to support the Target-Dialog header field. When used in a Supported header field, it implies that the sender of the message supports it. timer This option tag is for support of the [RFC4028] session timer extension. Inclusion in a Supported header field in a request or response indicates that the UA is capable of performing refreshes according to that specification. Inclusion in a Require header in a request means that the UAS must understand the session timer extension to process the request. Inclusion in a Require header field in a response indicates that the UAC must look for the Session-Expires header field in the response, and process accordingly. Registry Name: Warning Codes (warn-codes) Reference: [RFC3261] Section 27.2 Note: Warning codes provide information supplemental to the status code in SIP response messages when the failure of the transaction results from a Session Description Protocol (SDP) (RFC 2327 [1]) problem. Registry: Code Description Reference ---- --------------------------------------------------- --------- 300 Incompatible network protocol: One or more network [RFC3261] protocols contained in the session description are not available. 301 Incompatible network address formats: One or more [RFC3261] network address formats contained in the session description are not available. 302 Incompatible transport protocol: One or more [RFC3261] transport protocols described in the session description are not available. 303 Incompatible bandwidth units: One or more bandwidth [RFC3261] measurement units contained in the session description were not understood. 304 Media type not available: One or more media types [RFC3261] contained in the session description are not available. 305 Incompatible media format: One or more media formats [RFC3261] contained in the session description are not available. 306 Attribute not understood: One or more of the media [RFC3261] attributes in the session description are not supported. 307 Session description parameter not understood: A [RFC3261] parameter other than those listed above was not understood. 330 Multicast not available: The site where the user is [RFC3261] located does not support multicast. 331 Unicast not available: The site where the user is [RFC3261] located does not support unicast communication (usually due to the presence of a firewall). 370 Insufficient bandwidth: The bandwidth specified in [RFC3261] the session description or defined by the media exceeds that known to be available. 399 Miscellaneous warning: The warning text can include [RFC3261] arbitrary information to be presented to a human user or logged. A system receiving this warning MUST NOT take any automated action. Registry Name: Methods and Response Codes Reference: [RFC3261] Section 27.4 Registry: Methods Reference ------- --------- ACK [RFC3261] BYE [RFC3261] CANCEL [RFC3261] INFO [RFC2976] INVITE [RFC3261] MESSAGE [RFC3428] NOTIFY [RFC3265] OPTIONS [RFC3261] PRACK [RFC3262] PUBLISH [RFC3903] REFER [RFC3515] REGISTER [RFC3261] SUBSCRIBE [RFC3265] UPDATE [RFC3311] Registry Name: Response Codes Note: All response codes below are defined by [RFC3261] unless otherwise noted. Registry: Response Code Reference ------------------------------------------ --------- Provisional 1xx 100 Trying 180 Ringing 181 Call Is Being Forwarded 182 Queued 183 Session Progress Successful 2xx 200 OK 202 Accepted [RFC3265] Redirection 3xx 300 Multiple Choices 301 Moved Permanently 302 Moved Temporarily 305 Use Proxy 380 Alternative Service Request Failure 4xx 400 Bad Request 401 Unauthorized 402 Payment Required 403 Forbidden 404 Not Found 405 Method Not Allowed 406 Not Acceptable 407 Proxy Authentication Required 408 Request Timeout 410 Gone 412 Conditional Request Failed [RFC3903] 413 Request Entity Too Large 414 Request-URI Too Long 415 Unsupported Media Type 416 Unsupported URI Scheme 417 Unknown Resource-Priority [RFC4412] 420 Bad Extension 421 Extension Required 422 Session Interval Too Small [RFC4028] 423 Interval Too Brief 428 Use Identity Header [RFC4474] 429 Provide Referrer Identity [RFC3892] 433 Anonymity Disallowed [RFC5079] 436 Bad Identity-Info [RFC4474] 437 Unsupported Certificate [RFC4474] 438 Invalid Identity Header [RFC4474] 470 Consent Needed [RFC-ietf-sip-consent-framework-04.txt] 480 Temporarily Unavailable 481 Call/Transaction Does Not Exist 482 Loop Detected 483 Too Many Hops 484 Address Incomplete 485 Ambiguous 486 Busy Here 487 Request Terminated 488 Not Acceptable Here 489 Bad Event [RFC3265] 491 Request Pending 493 Undecipherable 494 Security Agreement Required [RFC3329] Server Failure 5xx 500 Server Internal Error 501 Not Implemented 502 Bad Gateway 503 Service Unavailable 504 Server Time-out 505 Version Not Supported 513 Message Too Large 580 Precondition Failure [RFC3312] Global Failures 6xx 600 Busy Everywhere 603 Decline 604 Does Not Exist Anywhere 606 Not Acceptable Registry Name: Security Mechanism Names Reference: [RFC3329] Section 6 Registry: Mechanism Name Reference -------------- --------- digest [RFC3329] tls [RFC3329] ipsec-ike [RFC3329] ipsec-man [RFC3329] ipsec-3gpp [RFC3329] Registry Name: Compression Schemes Reference: [RFC3486] Section 11 Registry: Compression Scheme Token Reference --------------------- --------- --------- Signaling Compression sigcomp [RFC3486] Registry Name: SIP/SIPS URI Parameters Reference: [RFC3969] Registration Procedures: Specification Required Registry: Parameter Name Predefined Values Reference -------------- ----------------- --------- cause Yes [RFC4458] comp Yes [RFC3486] content-type No [RFC4240] delay No [RFC4240] duration No [RFC4240] locale No [RFC4240] lr No [RFC3261] maddr No [RFC3261] method Yes [RFC3261] param[n] No [RFC4240] play No [RFC4240] repeat No [RFC4240] sigcomp-id No [RFC5049] target No [RFC4458] transport Yes [RFC3261] ttl No [RFC3261] user Yes [RFC3261][RFC4967] voicexml No [RFC4240] gr No [RFC-ietf-sip-gruu-15.txt] Registry Name: Header Field Parameters and Parameter Values Reference: [RFC3968] Registration Procedures: Published RFC (A standards-track RFC is NOT required) Registry: Predefined Header Field Parameter Name Values Reference ---------------------------- --------------------------- ---------- --------- Accept q No [RFC3261] Accept-Encoding q No [RFC3261] Accept-Language q No [RFC3261] Authorization algorithm Yes [RFC3261][RFC3310] Authorization auts No [RFC3310] Authorization cnonce No [RFC3261] Authorization nc No [RFC3261] Authorization nonce No [RFC3261] Authorization opaque No [RFC3261] Authorization qop Yes [RFC3261] Authorization realm No [RFC3261] Authorization response No [RFC3261] Authorization uri No [RFC3261] Authorization username No [RFC3261] Authentication-Info cnonce No [RFC3261] Authentication-Info nc No [RFC3261] Authentication-Info nextnonce No [RFC3261] Authentication-Info qop Yes [RFC3261] Authentication-Info rspauth No [RFC3261] Call-Info purpose Yes [RFC3261] Contact expires No [RFC3261] Contact q No [RFC3261] Contact pub-gruu No [RFC-ietf-sip-gruu-15.txt] Contact temp-gruu No [RFC-ietf-sip-gruu-15.txt] Content-Disposition handling Yes [RFC3261] Event call-id No [RFC4235] Event from-tag No [RFC4235] Event id No [RFC3265] Event include-session-description No [RFC4235] Event to-tag No [RFC4235] From tag No [RFC3261] P-Access-Network-Info cgi-3gpp No [RFC3455] P-Access-Network-Info utran-cell-id-3gpp No [RFC3455] P-Charging-Function-Addresses ccf No [RFC3455] P-Charging-Function-Addresses ecf No [RFC3455] P-Charging-Vector icid-value No [RFC3455] P-Charging-Vector icid-generated-at No [RFC3455] P-Charging-Vector orig-ioi No [RFC3455] P-Charging-Vector term-ioi No [RFC3455] P-DCS-Billing-Info called No [RFC3603] P-DCS-Billing-Info calling No [RFC3603] P-DCS-Billing-Info charge No [RFC3603] P-DCS-Billing-Info locroute No [RFC3603] P-DCS-Billing-Info rksgroup No [RFC3603] P-DCS-Billing-Info routing No [RFC3603] P-DCS-LAES content No [RFC3603] P-DCS-LAES key No [RFC3603] P-DCS-Redirect count No [RFC3603] P-DCS-Redirect redirector-uri No [RFC3603] Proxy-Authenticate algorithm Yes [RFC3261][RFC3310] Proxy-Authenticate domain No [RFC3261] Proxy-Authenticate nonce No [RFC3261] Proxy-Authenticate opaque No [RFC3261] Proxy-Authenticate qop Yes [RFC3261] Proxy-Authenticate realm No [RFC3261] Proxy-Authenticate stale Yes [RFC3261] Proxy-Authorization algorithm Yes [RFC3261][RFC3310] Proxy-Authorization auts No [RFC3310] Proxy-Authorization cnonce No [RFC3261] Proxy-Authorization nc No [RFC3261] Proxy-Authorization nonce No [RFC3261] Proxy-Authorization opaque No [RFC3261] Proxy-Authorization qop Yes [RFC3261] Proxy-Authorization realm No [RFC3261] Proxy-Authorization response No [RFC3261] Proxy-Authorization uri No [RFC3261] Proxy-Authorization username No [RFC3261] Reason cause Yes [RFC3326] Reason text No [RFC3326] Retry-After duration No [RFC3261] Security-Client alg Yes [RFC3329] Security-Client ealg Yes [RFC3329] Security-Client d-alg Yes [RFC3329] Security-Client d-qop Yes [RFC3329] Security-Client d-ver No [RFC3329] Security-Client mod Yes [RFC3329] Security-Client port1 No [RFC3329] Security-Client port2 No [RFC3329] Security-Client prot Yes [RFC3329] Security-Client q No [RFC3329] Security-Client spi No [RFC3329] Security-Server alg Yes [RFC3329] Security-Server ealg Yes [RFC3329] Security-Server d-alg Yes [RFC3329] Security-Server d-qop Yes [RFC3329] Security-Server d-ver No [RFC3329] Security-Server mod Yes [RFC3329] Security-Server port1 No [RFC3329] Security-Server port2 No [RFC3329] Security-Server prot Yes [RFC3329] Security-Server q No [RFC3329] Security-Server spi No [RFC3329] Security-Verify alg Yes [RFC3329] Security-Verify ealg Yes [RFC3329] Security-Verify d-alg Yes [RFC3329] Security-Verify d-qop Yes [RFC3329] Security-Verify d-ver No [RFC3329] Security-Verify mod Yes [RFC3329] Security-Verify port1 No [RFC3329] Security-Verify port2 No [RFC3329] Security-Verify prot Yes [RFC3329] Security-Verify q No [RFC3329] Security-Verify spi No [RFC3329] Subscription-State expires No [RFC3265] Subscription-State reason Yes [RFC3265] Subscription-State retry-after No [RFC3265] Target-Dialog local-tag No [RFC4538] Target-Dialog remote-tag No [RFC4538] To tag No [RFC3261] Trigger-Consent target-uri No [RFC-ietf-sip-consent-framework-04.txt] Via branch No [RFC3261] Via comp Yes [RFC3486] Via maddr No [RFC3261] Via received No [RFC3261] Via rport No [RFC3581] Via sigcomp-id No [RFC5049] Via ttl No [RFC3261] WWW-Authenticate algorithm Yes [RFC3261][RFC3310] WWW-Authenticate domain Yes [RFC3261] WWW-Authenticate nonce No [RFC3261] WWW-Authenticate opaque No [RFC3261] WWW-Authenticate qop Yes [RFC3261] WWW-Authenticate realm No [RFC3261] WWW-Authenticate stale Yes [RFC3261] Registry Name: URI Purposes Reference: [RFC4575] Registration Rules: Specification Required Registry: Value Description Reference --------------- ------------------------------------------ ---------- participation The URI can be used to join the conference [RFC4575] streaming The URI can be used to access the streamed [RFC4575] conference data event The URI can be used to subscribe to the [RFC4575] conference event package recording The URI can be used to access the recorded [RFC4575] conference data web-page The URI can be used to access a web page [RFC4575] that contains additional information of the conference Registry Name: Resource-Priority Namespaces Reference: [RFC4412] Registration Procedures: RFC publication Registry: Intended New warn- New resp. Namespace Levels Algorithm code code Reference --------- ------ ---------------- --------- --------- --------- dsn 5 preemption no no [RFC4412] drsn 6 preemption no no [RFC4412] q735 5 preemption no no [RFC4412] ets 5 queue no no [RFC4412] wps 5 queue no no [RFC4412] Legend ------ Namespace = the unique string identifying the namespace Levels = the number of priority-values within the namespace Algorithm = Intended operational behavior of SIP elements implementing this namespace New Warn code = New Warning Codes (warn-codes) introduced by this namespace New Resp. code = New SIP response codes introduced by this namespace Reference = IETF document reference for this namespace Registry Name: Resource-Priority Priority-values Reference: [RFC4412] Registration Procedures: RFC publication Registry: Namespace: drsn Reference: [RFC4412] Priority-Values (least to greatest): "routine", "priority", "immediate", "flash", "flash-override", "flash-override-override" Namespace: dsn Reference: [RFC4412] Priority-Values (least to greatest): "routine", "priority", "immediate", "flash", "flash-override" Namespace: q735 Reference: [RFC4412] Priority values (least to greatest): "4", "3", "2", "1", "0" Namespace: ets Reference: [RFC4412] Priority values (least to greatest): "4", "3", "2", "1", "0" Namespace: wps Reference: [RFC4412] Priority values (least to greatest): "4", "3", "2", "1", "0" Registry Name: Identity-Info Parameters Reference: [RFC4474] Registration Procedures: Standards Track RFC Registry: Parameter Name Reference ---------------------- --------- alg [RFC4474] Registry Name: Identity-Info Algorithm Parameter Values Reference: [RFC4474] Registration Procedures: Standards Track RFC 'alg' Parameter Name Reference ---------------------- --------- rsa-sha1 [RFC4474] References ---------- [RFC2976] S. Donovan, "The SIP INFO Method", RFC 2976, October 2000. [RFC3261] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC3262] J. Rosenberg and H. Schulzrinne, "Reliability of Provisional Responses in SIP", RFC 3262, June 2002. [RFC3265] A. Roach, "SIP-Specific Event Notification", RFC 3265, June 2002. [RFC3310] A. Niemi, J. Arkko, and V. Torvinen, "Hypertext Transfer Protocol (HTTP) Digest Authentication Using Authentication and Key Agreement (AKA), RFC 3310, September 2002. [RFC3311] J. Rosenberg, "The Session Initiation Protocol UPDATE Method", RFC 3311, September 2002. [RFC3312] G. Camarillo, W. Marshall, and J. Rosenberg, "Integration of Resource Management and SIP", RFC 3312, September 2002. [RFC3313] W. Marshall, F. Andreasen, D. Evans, and B. Beser, "SIP Extensions for Media Authorization", RFC 3313, September 2002. [RFC3323] J. Peterson, "A Privacy Mechanism for the Session Initiation Protocol (SIP), RFC 3323, November 2002. [RFC3325] C. Jennings, J. Peterson, M. Watson, "Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity within Trusted Networks", RFC 3325, November 2002. [RFC3326] H. Schulzrinne, D. Oran, and G. Camarillo, "The Reason Header Field for the Session Initiation Protocol", RFC 3326, November 2002. [RFC3327] D. Willis, B. Hoeneisen, "Session Initiation Protocol Extension Header Field for Registering Non-Adjacent Contacts", RFC 3327, November 2002. [RFC3329] J. Arkko, V. Torvinen, G. Camarillo, A. Niemi, and T. Haukka, "Security Mechanism Agreement for the Session Initiation Protocol (SIP)", RFC 3329, January 2003. [RFC3427] A. Mankin, S. Bradner, R. Mahy, D. Willis, J. Ott, and B. Rosen, "Change Process for the Session Initiation Protocol (SIP)", RFC 3427, November 2002. [RFC3428] B. Campbell, J. Rosenberg, H. Schulzrinne, C. Huitema, and D. Gurle, "Session Initiation Protocol Extension for Instant Messaging", RFC 3428, November 2002. [RFC3455] M. Garcia-Martin, E. Henrikson, and D. Mills, "Private Header (P-Header) Extensions to the Session Initiation Protocol (SIP) for the 3rd-Generation Partnership Project (3GPP)", RFC 3455, January 2003. [RFC3486] G. Camarillo, "Compressing the Session Initiation Protocol", RFC 3486, February 2003. [RFC3515] R. Sparks, "The SIP Refer Method", RFC 3515, April 2003. [RFC3581] J. Rosenberg and H. Schulzrinne, "An Extension to the Session Initiation Protocol (SIP) for Symmetric Response Routing", RFC 3581, August 2003. [RFC3603] W. Marshall, Ed. and F. Andreasen, Ed., "Private Session Initiation Protocol (SIP) Proxy-to-Proxy Extensions for Supporting the PacketCable Distributed Call Signaling Architecture", RFC 3603, October 2003. [RFC3608] D. Willis and B. Hoeneisen, "Session Initiation Protocol Extension Header Field for Service Route Discovery During Registration", RFC 3608, October 2003. [RFC3840] J. Rosenberg, H. Schulzrinne, and P. Kyzivat, "Indicating User Agent Capabilities in the Session Initiation Protocol", RFC 3840, August 2004. [RFC3841] J. Rosenberg, H. Schulzrinne, and P. Kyzivat, "Caller Preferences for the Session Initiation Protocol (SIP)", RFC 3841, August 2004. [RFC3891] R. Mahy, B. Biggs, and R. Dean, "The Session Inititation Protocol (SIP) "Replaces" Header", RFC 3891, September 2004. [RFC3892] R. Sparks, "The SIP Referred-By Mechanism", RFC 3892, September 2004. [RFC3903] A. Niemi, Ed., "An Event State Publication Extension to the Session Initiation", RFC 3903, October 2004. [RFC3911] R. Mahy and D. Petrie, "The Session Inititation Protocol (SIP) 'Join' Header", RFC 3911, October 2004. [RFC3959] G. Camarillo, "The Early Session Disposition Type for the Session Initiation Protocol (SIP)", RFC 3959, December 2004. [RFC3968] G. Camarillo, "The Internet Assigned Number Authority (IANA) Header Field Parameter Registry for the Session Initiation Protocol (SIP)", RFC 3968, December 2004. [RFC3969] G. Camarillo, "The Internet Assigned Number Authority (IANA) Universal Resource Identifier (URI) Parameter Registry for the Session", RFC 3969, December 2004. [RFC4028] S. Donovan and J. Rosenberg, "Session Timers in the Session Initiation Protocol (SIP)", RFC 4028, April 2005. [RFC4091] G. Camarillo and J. Rosenberg, "The Alternative Network Address Types Semantics (ANAT) for the Session Description Protocol (SDP) Grouping Framework", RFC 4091, June 2005. [RFC4092] G. Camarillo and J. Rosenberg, "Usage of the Session Description Protocol (SDP) Alternative Network Address Types (ANAT) Semantics in the Session Initiation Protocol", RFC 4092, June 2005. [RFC4235] J. Rosenberg, H. Schulzrinne, R. Mahy, "An INVITE-Initiated Dialog Event Package for the Session Initiation Protocol (SIP)", RFC 4235, November 2005. [RFC4240] E. Burger, Ed., J. Van Dyke, and A. Spitzer, "Basic Network Media Services with SIP", RFC 4240, December 2005. [RFC4244] M. Barnes, Ed., "An Extension to the Session Initiation Protocol for Request History Information", RFC 4244, November 2005. [RFC4575] J. Rosenberg, H. Schulzrinne and O. Levin, "A Session Initiation Protocol (SIP) Event Package for Conference State", RFC 4575, August 2006. [RFC4412] H. Schulzrinne and J. Polk, "Communications Resource Priority for the Session Initiation Protocol (SIP)", RFC 4412, February 2006. [RFC4411] J. M. Polk, "Extending the Session Initiation Protocol Reason Header for Preemption Events", RFC 4411, February 2006. [RFC4474] J. Peterson and C. Jennings, "Enhancements for Authenticated Identity Management in the Session Initiation Protocol (SIP)", RFC 4474, August 2006. [RFC4458] C. Jennings, F. Audet and J. Elwell, "Session Initiation Protocol (SIP) URIs for Applications such as Voicemail and Interactive Voice Response (IVR)", RFC 4458, April 2006. [RFC4457] G. Camarillo and G. Blanco, "The Session Initiation Protocol (SIP) P-User-Database Private-Header (P-Header)", RFC 4457, April 2006. [RFC4538] J. Rosenberg, "Request Authorization through Dialog Identification in the Session Initiation Protocol (SIP)", RFC 4538, June 2006. [RFC4662] J. Rosenberg and A. B. Roach, "A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists", RFC 4662, August 2006. [RFC4488] O. Levin, "Suppression of Session Initiation Protocol REFER Method Implicit", RFC 4488, May 2006. [RFC4916] J. Elwell, "Connected Identity in the Session Initiation Protocol (SIP)", RFC 4916, June 2007. [RFC4964] A. Allen, Ed., J. Holm, T. Hallin, "The P-Answer-State Header Extension to the Session Initiation Protocol for the Open Mobile Alliance Push-to-talk over Cellular", RFC 4964, September 2007. [RFC4967] B. Rosen, "Dialstring parameter for the Session Initiation Protocol Uniform Resource Identifier", RFC 4967, July 2007. [RFC5002] G. Camarillo, G. Blanco, "The Session Initiation Protocol (SIP) P-Profile-Key Private Header (P-Header)", RFC 5002, August 2007. [RFC5009] R. Ejza, "Private Header (P-Header) Extension to the Session Initiation Protocol (SIP) for Authorization of Early Media", RFC 5009, September 2007. [RFC5049] C. Bormann, Z. Liu, R. Price, G. Camarillo, Ed., "Applying Signaling Compression (SigComp) to the Session Initiation Protocol (SIP)", RFC 5049, December 2007. [RFC5079] J. Rosenberg, "Rejecting Anonymous Requests in the Session Initiation Protocol (SIP)", RFC 5079, December 2007. [RFC-ietf-sip-gruu-15.txt] J. Rosenberg, "Obtaining and Using Globally Routable User Agent (UA) URIs (GRUU) in the Session Initiation Protocol (SIP)", RFC XXXX, Month Year. [RFC-ietf-sip-consent-framework-04.txt] J. Rosenberg, G. Camarillo, Ed., D. Willis, " A Framework for Consent-based Communications in the Session Initiation Protocol (SIP)", RFC XXXX, Month Year. (registry created 2002) []