Microsoft recommends always adding user=phone to the Request-URI; without it the Direct Routing SIP proxy applies heuristics to decide whether the user part is a phone number or a SIP address.
Checked 2026-10-02
- Vendor
- Microsoft
- Product
- Teams Phone Direct Routing
- Subsystem
- Inbound call processing
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- current as of 2026-10-02
- Checked
- 2026-10-02
Sources
- Teams Phone System Direct Routing: SIP protocol — Microsoft · tier 2 current vendor documentation · Section 'Use of Request-URI parameter user=phone'
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting SIP 404 Not Found and 484 Address Incomplete call failures: source note sip-404-484-troubleshooting-teams-user-phone. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-404-484-troubleshooting-teams-user-phone
BibTeX
@misc{warmtransfer-claim-sip-404-484-troubleshooting-teams-user-phone,
title = {Troubleshooting SIP 404 Not Found and 484 Address Incomplete call failures: source note sip-404-484-troubleshooting-teams-user-phone},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-404-484-troubleshooting-teams-user-phone},
note = {Source note sip-404-484-troubleshooting-teams-user-phone, checked 2026-10-02}
}