Source note · Troubleshooting calls that drop on hold or transfer
The SBC must set the new INVITE's Request-URI only to the string in the Refer-To header, include the Referred-By header, and copy both strings from the REFER without changing them.
Checked 2026-09-30
- Vendor
- Microsoft
- Product
- Teams Phone Direct Routing
- Subsystem
- call-transfer
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- current as of 2026-09-30
- Checked
- 2026-09-30
Sources
- Issues with call transfers - Microsoft Teams — Microsoft · tier 2 current vendor documentation · Call transfer methods, REFER process steps 3 to 5
Cite this note
APA
WarmTransfer. (2026, September 30). Troubleshooting calls that drop on hold or transfer: source note sip-reinvite-call-drops-dr-refer-strings-unchanged. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-reinvite-call-drops-dr-refer-strings-unchanged
BibTeX
@misc{warmtransfer-claim-sip-reinvite-call-drops-dr-refer-strings-unchanged,
title = {Troubleshooting calls that drop on hold or transfer: source note sip-reinvite-call-drops-dr-refer-strings-unchanged},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-reinvite-call-drops-dr-refer-strings-unchanged},
note = {Source note sip-reinvite-call-drops-dr-refer-strings-unchanged, checked 2026-09-30}
}