Source note · Troubleshooting calls that drop on hold or transfer
Microsoft lists two causes for Direct Routing calls dropping before a transfer completes: the SIP proxy times out because the SBC sent no 202 Accepted or NOTIFY for the REFER, or the SBC's BYE arrives too early.
Checked 2026-09-30
The SIP BYE request from the SBC arrives too early, and the call ends before the transfer is completed fully.
- 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 · Calls drop before the transfer is completed
Cite this note
APA
WarmTransfer. (2026, September 30). Troubleshooting calls that drop on hold or transfer: source note sip-reinvite-call-drops-dr-transfer-drop-causes. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-reinvite-call-drops-dr-transfer-drop-causes
BibTeX
@misc{warmtransfer-claim-sip-reinvite-call-drops-dr-transfer-drop-causes,
title = {Troubleshooting calls that drop on hold or transfer: source note sip-reinvite-call-drops-dr-transfer-drop-causes},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-reinvite-call-drops-dr-transfer-drop-causes},
note = {Source note sip-reinvite-call-drops-dr-transfer-drop-causes, checked 2026-09-30}
}