Source note · SIP call forwarding and routing loops
When a Teams user forwards a call from a PSTN caller, the Direct Routing SIP proxy sends the caller a 181 Call Is Being Forwarded provisional response, and the forwarded INVITE's Request-URI carries a cause parameter.
Checked 2026-09-25
- Vendor
- Microsoft
- Product
- Teams Phone Direct Routing
- Subsystem
- call forwarding
- 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 · Call forwarding section, bullets
Cite this note
APA
WarmTransfer. (2026, September 25). SIP call forwarding and routing loops: source note sip-forwarding-loops-teams-dr-181. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-forwarding-loops-teams-dr-181
BibTeX
@misc{warmtransfer-claim-sip-forwarding-loops-teams-dr-181,
title = {SIP call forwarding and routing loops: source note sip-forwarding-loops-teams-dr-181},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-forwarding-loops-teams-dr-181},
note = {Source note sip-forwarding-loops-teams-dr-181, checked 2026-09-25}
}