Source note · SIP 503 and trunk out-of-service failures
In Teams Direct Routing, when the SBC gets a 503 with a Retry-After header in response to an INVITE, it must terminate that connection and try the next available Microsoft datacenter.
Checked 2026-09-25
When the SBC receives a 503 message with a Retry-After header in response to an INVITE, the SBC must terminate that connection and try the next available Microsoft datacenter.
- Vendor
- Microsoft
- Product
- Teams Phone Direct Routing
- Subsystem
- SIP signalling
- 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 'Retry-After'
Cite this note
APA
WarmTransfer. (2026, September 25). SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-dr-503-ra-next-dc. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-dr-503-ra-next-dc
BibTeX
@misc{warmtransfer-claim-sip-503-trunk-failures-dr-503-ra-next-dc,
title = {SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-dr-503-ra-next-dc},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-dr-503-ra-next-dc},
note = {Source note sip-503-trunk-failures-dr-503-ra-next-dc, checked 2026-09-25}
}