Source note · Troubleshooting Teams Direct Routing
If an INVITE or OPTIONS sent to the Microsoft SIP proxy has an IP address instead of an FQDN as the Contact header hostname, the proxy refuses it with 403 Forbidden. An IP address in Record-Route or Contact also fails the certificate check.
Checked 2026-09-25
- Vendor
- Microsoft
- Product
- Microsoft Teams Phone Direct Routing
- Subsystem
- sip-headers
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- current as of 2026-09-25
- Checked
- 2026-09-25
Sources
- Teams Phone System Direct Routing: SIP protocol — Microsoft · tier 2 current vendor documentation · Detailed requirements for Contact header and Request-URI > Contact header, final paragraph; Use of FQDN name in Contact or Record-Route
Cite this note
APA
WarmTransfer. (2026, September 25). Troubleshooting Teams Direct Routing: source note teams-direct-routing-troubleshooting-403-contact-ip. WarmTransfer. https://warmtransfer.net/knowledge/claims/teams-direct-routing-troubleshooting-403-contact-ip
BibTeX
@misc{warmtransfer-claim-teams-direct-routing-troubleshooting-403-contact-ip,
title = {Troubleshooting Teams Direct Routing: source note teams-direct-routing-troubleshooting-403-contact-ip},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/teams-direct-routing-troubleshooting-403-contact-ip},
note = {Source note teams-direct-routing-troubleshooting-403-contact-ip, checked 2026-09-25}
}