Source note · Troubleshooting fax over IP failures
The Cisco IOS fax protocol t38 command offers fallback modes cisco, none, or pass-through g711ulaw or g711alaw, used when T.38 cannot be negotiated at fax time.
Checked 2026-10-02
- Vendor
- Cisco
- Product
- Cisco IOS
- Subsystem
- fax protocol t38
- Deployment
- on-premises
- Region
- not restricted
- Release range
- IOS command reference dated 2007
- Checked
- 2026-10-02
Sources
- Cisco IOS Voice Command Reference - F — Cisco Systems · tier 2 current vendor documentation · fax protocol t38 (dial peer), Syntax Description
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting fax over IP failures: source note fax-over-ip-troubleshooting-t38-fallback-options. WarmTransfer. https://warmtransfer.net/knowledge/claims/fax-over-ip-troubleshooting-t38-fallback-options
BibTeX
@misc{warmtransfer-claim-fax-over-ip-troubleshooting-t38-fallback-options,
title = {Troubleshooting fax over IP failures: source note fax-over-ip-troubleshooting-t38-fallback-options},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/fax-over-ip-troubleshooting-t38-fallback-options},
note = {Source note fax-over-ip-troubleshooting-t38-fallback-options, checked 2026-10-02}
}