Source note · SIP TLS handshake failures on trunks
When certificates and SBC settings are correct but the TLS connection is still interrupted, Microsoft points to intermediary devices such as firewalls or routers between the SBC and Microsoft closing the connection.
Checked 2026-09-25
- Vendor
- Microsoft
- Product
- Teams Phone Direct Routing
- Subsystem
- network path
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- current as of 2026-09-25
- Checked
- 2026-09-25
Sources
- SBC connectivity issues — Microsoft · tier 2 current vendor documentation · TLS connection issues > SBC connection is interrupted
Cite this note
APA
WarmTransfer. (2026, September 25). SIP TLS handshake failures on trunks: source note sip-tls-handshake-failures-dr-middlebox-closes. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-tls-handshake-failures-dr-middlebox-closes
BibTeX
@misc{warmtransfer-claim-sip-tls-handshake-failures-dr-middlebox-closes,
title = {SIP TLS handshake failures on trunks: source note sip-tls-handshake-failures-dr-middlebox-closes},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-tls-handshake-failures-dr-middlebox-closes},
note = {Source note sip-tls-handshake-failures-dr-middlebox-closes, checked 2026-09-25}
}