Source note · Calls that drop after about 30 seconds
An RFC 3581 client may add an empty 'rport' parameter to the top Via header to signal that it supports symmetric response routing.
Checked 2026-09-25
- Vendor
- IETF
- Product
- SIP
- Subsystem
- NAT traversal / Via
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3581
- Checked
- 2026-09-25
Sources
- RFC 3581: An Extension to the Session Initiation Protocol (SIP) for Symmetric Response Routing — IETF / RFC Editor · tier 1 standards and regulators · Client behaviour section
Cite this note
APA
WarmTransfer. (2026, September 25). Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-rport-client. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-rport-client
BibTeX
@misc{warmtransfer-claim-sip-calls-drop-30-seconds-rport-client,
title = {Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-rport-client},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-rport-client},
note = {Source note sip-calls-drop-30-seconds-rport-client, checked 2026-09-25}
}