Source note · Calls that drop after about 30 seconds
Direct Routing does not support an IP address in Record-Route or Contact. Only an FQDN that matches the SBC certificate's CN or SAN is supported, and an IP address or mismatched FQDN makes the call fail.
Checked 2026-09-25
Use of an IP address isn't supported in either Record-Route or Contact.
- Vendor
- Microsoft
- Product
- Teams Phone Direct Routing
- Subsystem
- SIP proxy
- 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 · Section 'Use of FQDN name in Contact or Record-Route'
Cite this note
APA
WarmTransfer. (2026, September 25). Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-msdr-no-ip-in-rr. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-msdr-no-ip-in-rr
BibTeX
@misc{warmtransfer-claim-sip-calls-drop-30-seconds-msdr-no-ip-in-rr,
title = {Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-msdr-no-ip-in-rr},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-msdr-no-ip-in-rr},
note = {Source note sip-calls-drop-30-seconds-msdr-no-ip-in-rr, checked 2026-09-25}
}