| 2119 | Key words for use in RFCs to Indicate Requirement LevelsS. Bradner | Best Current Practice | March 1997 |
| 2183 | Communicating Presentation Information in Internet Messages: The Content-Disposition Header FieldR. Troost, S. Dorner, K. Moore, Ed. | Proposed Standard | August 1997 |
| 2617 | HTTP Authentication: Basic and Digest Access AuthenticationJ. Franks, P. Hallam-Baker, J. Hostetler, S. Lawrence, P. Leach, A. Luotonen, L. Stewart · obsoleted by RFC 7235, RFC 7615, RFC 7616, RFC 7617 | Draft Standard | June 1999 |
| 3204 | MIME media types for ISUP and QSIG ObjectsE. Zimmerer, J. Peterson, A. Vemuri, L. Ong, F. Audet, M. Watson, M. Zonoun | Proposed Standard | December 2001 |
| 3248 | A Delay Bound alternative revision of RFC 2598G. Armitage, B. Carpenter, A. Casati, J. Crowcroft, J. Halpern, B. Kumar, J. Schnizlein | Informational | March 2002 |
| 3261 | SIP: Session Initiation ProtocolJ. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, E. Schooler | Proposed Standard | July 2002 |
| 3323 | A Privacy Mechanism for the Session Initiation Protocol (SIP)J. Peterson | Proposed Standard | December 2002 |
| 3325 | Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity within Trusted NetworksC. Jennings, J. Peterson, M. Watson | Informational | December 2002 |
| 3428 | Session Initiation Protocol (SIP) Extension for Instant MessagingB. Campbell, Ed., J. Rosenberg, H. Schulzrinne, C. Huitema, D. Gurle | Proposed Standard | December 2002 |
| 3851 | Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Message SpecificationB. Ramsdell, Ed. · obsoleted by RFC 5751 | Proposed Standard | July 2004 |
| 4825 | The Extensible Markup Language (XML) Configuration Access Protocol (XCAP)J. Rosenberg | Proposed Standard | May 2007 |
| 4826 | Extensible Markup Language (XML) Formats for Representing Resource ListsJ. Rosenberg | Proposed Standard | May 2007 |
| 4975 | The Message Session Relay Protocol (MSRP)B. Campbell, Ed., R. Mahy, Ed., C. Jennings, Ed. | Proposed Standard | September 2007 |
| 5363 | Framework and Security Considerations for Session Initiation Protocol (SIP) URI-List ServicesG. Camarillo, A.B. Roach | Proposed Standard | October 2008 |
| 5364 | Extensible Markup Language (XML) Format Extension for Representing Copy Control Attributes in Resource ListsM. Garcia-Martin, G. Camarillo | Proposed Standard | October 2008 |