| 2045 | Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message BodiesN. Freed, N. Borenstein | Draft Standard | November 1996 |
| 2046 | Multipurpose Internet Mail Extensions (MIME) Part Two: Media TypesN. Freed, N. Borenstein | Draft Standard | November 1996 |
| 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 |
| 3217 | Triple-DES and RC2 Key WrappingR. Housley | Informational | December 2001 |
| 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 |
| 3268 | Advanced Encryption Standard (AES) Ciphersuites for Transport Layer Security (TLS)P. Chown · obsoleted by RFC 5246 | Proposed Standard | July 2002 |
| 3280 | Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) ProfileR. Housley, W. Polk, W. Ford, D. Solo · obsoleted by RFC 5280 | Proposed Standard | May 2002 |
| 3311 | The Session Initiation Protocol (SIP) UPDATE MethodJ. Rosenberg | Proposed Standard | October 2002 |
| 3428 | Session Initiation Protocol (SIP) Extension for Instant MessagingB. Campbell, Ed., J. Rosenberg, H. Schulzrinne, C. Huitema, D. Gurle | Proposed Standard | December 2002 |
| 3629 | UTF-8, a transformation format of ISO 10646F. Yergeau | Internet Standard | November 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 |
| 3851 | Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Message SpecificationB. Ramsdell, Ed. · obsoleted by RFC 5751 | Proposed Standard | July 2004 |
| 3860 | Common Profile for Instant Messaging (CPIM)J. Peterson | Proposed Standard | August 2004 |
| 3861 | Address Resolution for Instant Messaging and PresenceJ. Peterson | Proposed Standard | August 2004 |
| 3862 | Common Presence and Instant Messaging (CPIM): Message FormatG. Klyne, D. Atkins | Proposed Standard | August 2004 |
| 3921 | Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and PresenceP. Saint-Andre, Ed. · obsoleted by RFC 6121 | Proposed Standard | October 2004 |
| 3960 | Early Media and Ringing Tone Generation in the Session Initiation Protocol (SIP)G. Camarillo, H. Schulzrinne | Informational | December 2004 |
| 3986 | Uniform Resource Identifier (URI): Generic SyntaxT. Berners-Lee, R. Fielding, L. Masinter | Internet Standard | January 2005 |
| 4145 | TCP-Based Media Transport in the Session Description Protocol (SDP)D. Yon, G. Camarillo | Proposed Standard | September 2005 |
| 4234 | Augmented BNF for Syntax Specifications: ABNFD. Crocker, Ed., P. Overell · obsoleted by RFC 5234 | Draft Standard | October 2005 |
| 4346 | The Transport Layer Security (TLS) Protocol Version 1.1T. Dierks, E. Rescorla · obsoleted by RFC 5246 | 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 |
| 4566 | SDP: Session Description ProtocolM. Handley, V. Jacobson, C. Perkins · obsoleted by RFC 8866 | Proposed Standard | July 2006 |
| 4572 | Connection-Oriented Media Transport over the Transport Layer Security (TLS) Protocol in the Session Description Protocol (SDP)J. Lennox · obsoleted by RFC 8122 | Proposed Standard | July 2006 |
| 4976 | Relay Extensions for the Message Sessions Relay Protocol (MSRP)C. Jennings, R. Mahy, A. B. Roach | Proposed Standard | September 2007 |