Source note · Troubleshooting SIP 403 Forbidden from a carrier
Microsoft states that when an SBC returns a failure to Teams on an outbound Direct Routing call, a SIP 403 or 404 most likely means the PSTN provider is sending the failure, and the resolution is to contact the PSTN provider.
Checked 2026-09-30
This is most likely the case if the failure error code is SIP 403 or SIP 404.
- Vendor
- Microsoft
- Product
- Teams Phone Direct Routing
- Subsystem
- outbound calls
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- current as of 2026-09-30
- Checked
- 2026-09-30
Sources
- Issues with outbound calls - Microsoft Teams — Microsoft · tier 2 current vendor documentation · Connection to the SBC not established > Cause 2 and Resolution 2
Cite this note
APA
WarmTransfer. (2026, September 30). Troubleshooting SIP 403 Forbidden from a carrier: source note sip-403-forbidden-troubleshooting-ms-pstn-provider. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-403-forbidden-troubleshooting-ms-pstn-provider
BibTeX
@misc{warmtransfer-claim-sip-403-forbidden-troubleshooting-ms-pstn-provider,
title = {Troubleshooting SIP 403 Forbidden from a carrier: source note sip-403-forbidden-troubleshooting-ms-pstn-provider},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-403-forbidden-troubleshooting-ms-pstn-provider},
note = {Source note sip-403-forbidden-troubleshooting-ms-pstn-provider, checked 2026-09-30}
}