| 2104 | HMAC: Keyed-Hashing for Message AuthenticationH. Krawczyk, M. Bellare, R. Canetti | Informational | February 1997 |
| 2119 | Key words for use in RFCs to Indicate Requirement LevelsS. Bradner | Best Current Practice | March 1997 |
| 3261 | SIP: Session Initiation ProtocolJ. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, E. Schooler | Proposed Standard | July 2002 |
| 3263 | Session Initiation Protocol (SIP): Locating SIP ServersJ. Rosenberg, H. Schulzrinne | Proposed Standard | July 2002 |
| 3265 | Session Initiation Protocol (SIP)-Specific Event NotificationA. B. Roach · obsoleted by RFC 6665 | Proposed Standard | July 2002 |
| 3327 | Session Initiation Protocol (SIP) Extension Header Field for Registering Non-Adjacent ContactsD. Willis, B. Hoeneisen | Proposed Standard | December 2002 |
| 3608 | Session Initiation Protocol (SIP) Extension Header Field for Service Route Discovery During RegistrationD. Willis, B. Hoeneisen | Proposed Standard | October 2003 |
| 3680 | A Session Initiation Protocol (SIP) Event Package for RegistrationsJ. Rosenberg | Proposed Standard | March 2004 |
| 3840 | Indicating User Agent Capabilities in the Session Initiation Protocol (SIP)J. Rosenberg, H. Schulzrinne, P. Kyzivat | Proposed Standard | August 2004 |
| 3841 | Caller Preferences for the Session Initiation Protocol (SIP)J. Rosenberg, H. Schulzrinne, P. Kyzivat | Proposed Standard | August 2004 |
| 3966 | The tel URI for Telephone NumbersH. Schulzrinne | Proposed Standard | December 2004 |
| 3968 | The Internet Assigned Number Authority (IANA) Header Field Parameter Registry for the Session Initiation Protocol (SIP)G. Camarillo | Best Current Practice | December 2004 |
| 3969 | The Internet Assigned Number Authority (IANA) Uniform Resource Identifier (URI) Parameter Registry for the Session Initiation Protocol (SIP)G. Camarillo | Best Current Practice | December 2004 |
| 4086 | Randomness Requirements for SecurityD. Eastlake 3rd, J. Schiller, S. Crocker | Best Current Practice | June 2005 |
| 4475 | Session Initiation Protocol (SIP) Torture Test MessagesR. Sparks, Ed., A. Hawrylyshen, A. Johnston, J. Rosenberg, H. Schulzrinne | Informational | May 2006 |
| 4648 | The Base16, Base32, and Base64 Data EncodingsS. Josefsson | Proposed Standard | October 2006 |
| 5246 | The Transport Layer Security (TLS) Protocol Version 1.2T. Dierks, E. Rescorla · obsoleted by RFC 8446, RFC 9846 | Proposed Standard | August 2008 |
| 5626 | Managing Client-Initiated Connections in the Session Initiation Protocol (SIP)C. Jennings, Ed., R. Mahy, Ed., F. Audet, Ed. | Proposed Standard | October 2009 |
| 5627 | Obtaining and Using Globally Routable User Agent URIs (GRUUs) in the Session Initiation Protocol (SIP)J. Rosenberg | Proposed Standard | October 2009 |
| 5628 | Registration Event Package Extension for Session Initiation Protocol (SIP) Globally Routable User Agent URIs (GRUUs)P. Kyzivat | Proposed Standard | October 2009 |
| 5727 | Change Process for the Session Initiation Protocol (SIP) and the Real-time Applications and Infrastructure AreaJ. Peterson, C. Jennings, R. Sparks | Best Current Practice | March 2010 |
| 5741 | RFC Streams, Headers, and BoilerplatesL. Daigle, Ed., O. Kolkman, Ed., IAB · obsoleted by RFC 7841 | Informational | December 2009 |
| 5947 | Requirements for Multiple Address of Record (AOR) Reachability Information in the Session Initiation Protocol (SIP)J. Elwell, H. Kaplan | Informational | September 2010 |