| 2608 | Service Location Protocol, Version 2E. Guttman, C. Perkins, J. Veizades, M. Day | Proposed Standard | June 1999 |
| 3261 | SIP: Session Initiation ProtocolJ. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, E. Schooler | Proposed Standard | July 2002 |
| 3264 | An Offer/Answer Model with Session Description Protocol (SDP)J. Rosenberg, H. Schulzrinne | Proposed Standard | July 2002 |
| 3428 | Session Initiation Protocol (SIP) Extension for Instant MessagingB. Campbell, Ed., J. Rosenberg, H. Schulzrinne, C. Huitema, D. Gurle | Proposed Standard | December 2002 |
| 3515 | The Session Initiation Protocol (SIP) Refer MethodR. Sparks | Proposed Standard | April 2003 |
| 3725 | Best Current Practices for Third Party Call Control (3pcc) in the Session Initiation Protocol (SIP)J. Rosenberg, J. Peterson, H. Schulzrinne, G. Camarillo | Best Current Practice | April 2004 |
| 3840 | Indicating User Agent Capabilities in the Session Initiation Protocol (SIP)J. Rosenberg, H. Schulzrinne, P. Kyzivat | Proposed Standard | August 2004 |
| 3880 | Call Processing Language (CPL): A Language for User Control of Internet Telephony ServicesJ. Lennox, X. Wu, H. Schulzrinne | Proposed Standard | November 2004 |
| 3891 | The Session Initiation Protocol (SIP) "Replaces" HeaderR. Mahy, B. Biggs, R. Dean | Proposed Standard | September 2004 |
| 3892 | The Session Initiation Protocol (SIP) Referred-By MechanismR. Sparks | Proposed Standard | September 2004 |
| 4103 | RTP Payload for Text ConversationG. Hellstrom, P. Jones | Proposed Standard | June 2005 |
| 4145 | TCP-Based Media Transport in the Session Description Protocol (SDP)D. Yon, G. Camarillo | Proposed Standard | September 2005 |
| 4235 | An INVITE-Initiated Dialog Event Package for the Session Initiation Protocol (SIP)J. Rosenberg, H. Schulzrinne, R. Mahy, Ed. | Proposed Standard | November 2005 |
| 4347 | Datagram Transport Layer SecurityE. Rescorla, N. Modadugu · obsoleted by RFC 6347 | Historic | April 2006 |
| 4474 | Enhancements for Authenticated Identity Management in the Session Initiation Protocol (SIP)J. Peterson, C. Jennings · obsoleted by RFC 8224 | Proposed Standard | August 2006 |
| 4484 | Trait-Based Authorization Requirements for the Session Initiation Protocol (SIP)J. Peterson, J. Polk, D. Sicker, H. Tschofenig | Informational | August 2006 |
| 4569 | Internet Assigned Number Authority (IANA) Registration of the Message Media Feature TagG. Camarillo | Informational | July 2006 |
| 4629 | RTP Payload Format for ITU-T Rec. H.263 VideoJ. Ott, C. Bormann, G. Sullivan, S. Wenger, R. Even, Ed. | Proposed Standard | January 2007 |
| 4975 | The Message Session Relay Protocol (MSRP)B. Campbell, Ed., R. Mahy, Ed., C. Jennings, Ed. | Proposed Standard | September 2007 |
| 4976 | Relay Extensions for the Message Sessions Relay Protocol (MSRP)C. Jennings, R. Mahy, A. B. Roach | Proposed Standard | September 2007 |
| 5389 | Session Traversal Utilities for NAT (STUN)J. Rosenberg, R. Mahy, P. Matthews, D. Wing · obsoleted by RFC 8489 | Proposed Standard | October 2008 |
| 5627 | Obtaining and Using Globally Routable User Agent URIs (GRUUs) in the Session Initiation Protocol (SIP)J. Rosenberg | Proposed Standard | October 2009 |