RFC 7647 — Clarifications for the Use of REFER with RFC 6665

Publisher

IETF / RFC Editor

URL

https://www.rfc-editor.org/rfc/rfc7647.html

Published

2015-09

Updated

unknown

Accessed

2026-09-16

HTTP status

200

License

IETF Trust / BCP 78; permitted with the RFC's own copyright and license notices intact

Source notes citing this source

• RFC 7647 deprecates the 202 response code for REFER: an element accepting a REFER request must not reply with 202, must treat any 202 it receives as identical to a 200, and must send 200 wherever RFC 3515 requires 202. Accepting a REFER with any 2xx still obliges the recipient to create a subscription and notify the status of the refer. in context
• RFC 7647 makes a Globally Routable User Agent URI mandatory for a notifier: a user agent accepting a REFER that creates a subscription must populate its Contact header field with one, and a user agent that might become a notifier needs to include one in the Contact of dialog-forming and target-refresh methods such as INVITE. in context
• RFC 7647 prohibits dialog reuse for REFER: where the peer in an existing dialog has provided a Globally Routable User Agent URI as its contact, a user agent constructing a REFER that could create an implicit subscription must build it as an out-of-dialog message, so the REFER carries no tag in its To header field. The exception is a peer that is an older RFC 3515 implementation, identified by the absence of such a URI in the remote target. in context
• RFC 7647 requires that a user agent wishing to identify an existing dialog, such as for call transfer as defined in RFC 5589, uses the Target-Dialog extension of RFC 4538, and that user agents accepting REFER are able to process that extension in requests they receive. in context

Cite this source record

APA

WarmTransfer. (n.d.). RFC 7647 — Clarifications for the Use of REFER with RFC 6665. WarmTransfer. https://warmtransfer.net/knowledge/sources/rfc-7647-refer-clarifications

BibTeX

@misc{warmtransfer-rfc-7647-refer-clarifications,
  title  = {RFC 7647 — Clarifications for the Use of REFER with RFC 6665},
  author = {{WarmTransfer}},
  year   = {2015},
  url    = {https://warmtransfer.net/knowledge/sources/rfc-7647-refer-clarifications},
  note   = {IETF / RFC Editor, accessed 2026-09-16}
}