Source note · Troubleshooting fax over IP failures
For a T.38 re-INVITE rejected with SIP 488 on CUBE, Cisco advises checking that T.38 is configured globally and on both the incoming and outgoing dial-peers, then using debug ccsip to see why SIP rejected the re-INVITE.
Checked 2026-10-02
- Vendor
- Cisco
- Product
- Cisco Unified Border Element
- Subsystem
- T.38 negotiation
- Deployment
- on-premises
- Region
- not restricted
- Release range
- as documented 2013-08-14
- Checked
- 2026-10-02
Sources
- CUBE Third-Party Interoperability Fax Guidelines — Cisco · tier 2 current vendor documentation · Troubleshoot section (488 Not Acceptable Media)
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting fax over IP failures: source note fax-over-ip-troubleshooting-488-check-dial-peers. WarmTransfer. https://warmtransfer.net/knowledge/claims/fax-over-ip-troubleshooting-488-check-dial-peers
BibTeX
@misc{warmtransfer-claim-fax-over-ip-troubleshooting-488-check-dial-peers,
title = {Troubleshooting fax over IP failures: source note fax-over-ip-troubleshooting-488-check-dial-peers},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/fax-over-ip-troubleshooting-488-check-dial-peers},
note = {Source note fax-over-ip-troubleshooting-488-check-dial-peers, checked 2026-10-02}
}