Source note · Troubleshooting calls that drop on hold or transfer
After receiving a REFER from the Microsoft SIP proxy, the SBC must send the new INVITE back to the SIP proxy, not to the PSTN or any other destination, even when the transfer target is an external PSTN number.
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 step 2
Cite this note
APA
WarmTransfer. (2026, September 30). Troubleshooting calls that drop on hold or transfer: source note sip-reinvite-call-drops-dr-refer-invite-to-proxy. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-reinvite-call-drops-dr-refer-invite-to-proxy
BibTeX
@misc{warmtransfer-claim-sip-reinvite-call-drops-dr-refer-invite-to-proxy,
title = {Troubleshooting calls that drop on hold or transfer: source note sip-reinvite-call-drops-dr-refer-invite-to-proxy},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-reinvite-call-drops-dr-refer-invite-to-proxy},
note = {Source note sip-reinvite-call-drops-dr-refer-invite-to-proxy, checked 2026-09-30}
}