Source note · Calls that drop after about 30 seconds
If a proxy puts a numeric-IP Record-Route without a transport parameter, later in-dialog requests such as ACK or BYE default to UDP under RFC 3263 procedures. When the other side of the proxy used TCP, those requests fail.
Checked 2026-09-25
- Vendor
- IETF
- Product
- SIP
- Subsystem
- Record-Route
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 5658
- Checked
- 2026-09-25
Sources
- RFC 5658: Addressing Record-Route Issues in the Session Initiation Protocol (SIP) — IETF / RFC Editor · tier 1 standards and regulators · Section 6.1, Figure 4
Cite this note
APA
WarmTransfer. (2026, September 25). Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-rr-transport-mismatch. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-rr-transport-mismatch
BibTeX
@misc{warmtransfer-claim-sip-calls-drop-30-seconds-rr-transport-mismatch,
title = {Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-rr-transport-mismatch},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-rr-transport-mismatch},
note = {Source note sip-calls-drop-30-seconds-rr-transport-mismatch, checked 2026-09-25}
}