Source note · Troubleshooting fax over IP failures
Cisco gateways support only G3 fax over T.38; on an SG3 call the originating gateway squelches the V.8 CM tone so the SG3 machines fall back to G3.
Checked 2026-10-02
Cisco gateways only support G3 fax calls with T.38.
- Vendor
- Cisco
- Product
- Cisco IOS voice gateways
- Subsystem
- Super G3 handling
- Deployment
- on-premises
- Region
- not restricted
- Release range
- as documented 2015
- Checked
- 2026-10-02
Sources
- Fax-SIP Troubleshoot Guide — Cisco Systems · tier 2 current vendor documentation · SG3 fax over T.38 section
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting fax over IP failures: source note fax-over-ip-troubleshooting-cisco-t38-g3-only. WarmTransfer. https://warmtransfer.net/knowledge/claims/fax-over-ip-troubleshooting-cisco-t38-g3-only
BibTeX
@misc{warmtransfer-claim-fax-over-ip-troubleshooting-cisco-t38-g3-only,
title = {Troubleshooting fax over IP failures: source note fax-over-ip-troubleshooting-cisco-t38-g3-only},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/fax-over-ip-troubleshooting-cisco-t38-g3-only},
note = {Source note fax-over-ip-troubleshooting-cisco-t38-g3-only, checked 2026-10-02}
}