Source note · Troubleshooting fax over IP failures
For fax pass-through testing on Cisco gateways, echo cancellation and voice activity detection should be disabled (no echo-cancel enable, no vad) because they degrade modulated fax signals.
Checked 2026-10-02
- Vendor
- Cisco
- Product
- Cisco IOS voice gateways
- Subsystem
- pass-through
- Deployment
- on-premises
- Region
- not restricted
- Release range
- current as of 2026-10-02
- Checked
- 2026-10-02
Sources
- Troubleshoot Fax Relay — Cisco Systems · tier 2 current vendor documentation · Fax pass-through section
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting fax over IP failures: source note fax-over-ip-troubleshooting-passthru-no-ec-vad. WarmTransfer. https://warmtransfer.net/knowledge/claims/fax-over-ip-troubleshooting-passthru-no-ec-vad
BibTeX
@misc{warmtransfer-claim-fax-over-ip-troubleshooting-passthru-no-ec-vad,
title = {Troubleshooting fax over IP failures: source note fax-over-ip-troubleshooting-passthru-no-ec-vad},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/fax-over-ip-troubleshooting-passthru-no-ec-vad},
note = {Source note fax-over-ip-troubleshooting-passthru-no-ec-vad, checked 2026-10-02}
}