RFC 4321: Problems Identified Associated with the Session Initiation Protocol's (SIP) Non-INVITE Transaction

Publisher

IETF / RFC Editor

URL

https://www.rfc-editor.org/rfc/rfc4321.html

Published

2006-01-01

Updated

unknown

Accessed

2026-10-02

HTTP status

200

License

IETF Trust legal provisions (BCP 78); no-redistribution; short excerpts and locators only

Source notes citing this source

• RFC 4321 notes that a SIP proxy cannot reliably distinguish an element that has failed from one that is merely slow to respond, which complicates blacklisting of unresponsive next hops. in context
• RFC 4321 observes that most endpoints emit a 408 for a non-INVITE request 64*T1 after receiving it if no earlier final response was sent, and that such a 408 reaches the upstream element too late to be useful. in context
• For a non-INVITE client transaction, Timer E starts at T1 and doubles on each firing while in Trying, capping at T2; after a provisional response it retransmits every T2. in context
• The non-INVITE transaction timeout Timer F is 64*T1, which is 32 seconds with default timers. in context

Cite this source record

APA

WarmTransfer. (2006, January 1). RFC 4321: Problems Identified Associated with the Session Initiation Protocol's (SIP) Non-INVITE Transaction. WarmTransfer. https://warmtransfer.net/knowledge/sources/rfc-4321-non-invite-problems

BibTeX

@misc{warmtransfer-rfc-4321-non-invite-problems,
  title  = {RFC 4321: Problems Identified Associated with the Session Initiation Protocol's (SIP) Non-INVITE Transaction},
  author = {{WarmTransfer}},
  year   = {2006},
  url    = {https://warmtransfer.net/knowledge/sources/rfc-4321-non-invite-problems},
  note   = {IETF / RFC Editor, accessed 2026-10-02}
}