Microsoft response code 560503 with SIP 503 means the SBC itself returned 503 (maintenance or overload). Microsoft says to check the SBC logs, check that the SBC is licensed for the concurrent session count, and see whether the failures cluster on a particular destination country or calling corridor.

Checked 2026-09-25

Vendor
Microsoft
Product
Microsoft Teams Phone Direct Routing
Subsystem
sip-response-codes
Deployment
multi-tenant
Region
not restricted
Release range
current as of 2026-09-25
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). Troubleshooting Teams Direct Routing: source note teams-direct-routing-troubleshooting-503-560503. WarmTransfer. https://warmtransfer.net/knowledge/claims/teams-direct-routing-troubleshooting-503-560503

BibTeX

@misc{warmtransfer-claim-teams-direct-routing-troubleshooting-503-560503,
  title  = {Troubleshooting Teams Direct Routing: source note teams-direct-routing-troubleshooting-503-560503},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/teams-direct-routing-troubleshooting-503-560503},
  note   = {Source note teams-direct-routing-troubleshooting-503-560503, checked 2026-09-25}
}

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