Source note · One-way and no-way audio diagnosis
Cisco describes a no-way audio failure specific to hairpin calls, where a call arriving from an internet telephony service provider is forwarded or transferred back to that provider: some providers disregard the IP address and port in the SDP because of their firewall implementation and transmit only to the source address of RTP they have already received, and on a hairpin call neither end sends first because the IP phone that would normally send dummy RTP after opening its ports is not in the path.
Checked 2026-09-16
- Vendor
- Cisco
- Product
- Cisco Unified Border Element
- Subsystem
- media
- Deployment
- not restricted
- Region
- not restricted
- Release range
- not restricted
- Checked
- 2026-09-16
Sources
- Troubleshoot No-way Audio Issue with Hairpin Calls on CUBE — Cisco Systems, Inc. (www.cisco.com) · tier 2 current vendor documentation · Problem section
Cite this note
APA
WarmTransfer. (2026, September 16). One-way and no-way audio diagnosis: source note owa-hairpin-neither-side-sends-first. WarmTransfer. https://warmtransfer.net/knowledge/claims/owa-hairpin-neither-side-sends-first
BibTeX
@misc{warmtransfer-claim-owa-hairpin-neither-side-sends-first,
title = {One-way and no-way audio diagnosis: source note owa-hairpin-neither-side-sends-first},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/owa-hairpin-neither-side-sends-first},
note = {Source note owa-hairpin-neither-side-sends-first, checked 2026-09-16}
}