Source note · SIP 503 and trunk out-of-service failures
Direct Routing Microsoft response code 540998 with SIP 503 (Service state Inactive/DrainingTransactions) is expected while Microsoft SIP endpoints are down for maintenance and normally needs no action.
Checked 2026-09-25
This error is expected when Microsoft SIP endpoints are temporarily unavailable for maintenance.
- Vendor
- Microsoft
- Product
- Teams Phone Direct Routing
- Subsystem
- call failure codes
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- current as of 2026-09-25
- Checked
- 2026-09-25
Sources
- SIP 503 and Microsoft response codes - Microsoft Teams — Microsoft · tier 2 current vendor documentation · Section '540998 503 Service Unavailable - Service state: Inactive/DrainingTransactions'
Cite this note
APA
WarmTransfer. (2026, September 25). SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-dr-540998-maintenance. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-dr-540998-maintenance
BibTeX
@misc{warmtransfer-claim-sip-503-trunk-failures-dr-540998-maintenance,
title = {SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-dr-540998-maintenance},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-dr-540998-maintenance},
note = {Source note sip-503-trunk-failures-dr-540998-maintenance, checked 2026-09-25}
}