Source note · Fax and T.38 in cloud calling
A documented Webex Calling fax failure is that the T.38 switchover ReINVITE from a registered fax device is answered with SIP 488 Not Acceptable Here so T.38 is never negotiated.
Checked 2026-09-24
- Vendor
- Cisco
- Product
- Webex Calling
- Subsystem
- T.38 negotiation
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- as of 2024-07-18
- Checked
- 2026-09-24
Sources
- Fix 488 SIP Error for Fax T.38 ReINVITE Rejected by Webex Calling — Cisco · tier 2 current vendor documentation · Problem section
Cite this note
APA
WarmTransfer. (2026, September 24). Fax and T.38 in cloud calling: source note fax-t38-wxc-488-reinvite-symptom. WarmTransfer. https://warmtransfer.net/knowledge/claims/fax-t38-wxc-488-reinvite-symptom
BibTeX
@misc{warmtransfer-claim-fax-t38-wxc-488-reinvite-symptom,
title = {Fax and T.38 in cloud calling: source note fax-t38-wxc-488-reinvite-symptom},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/fax-t38-wxc-488-reinvite-symptom},
note = {Source note fax-t38-wxc-488-reinvite-symptom, checked 2026-09-24}
}