Microsoft says 500001/408 usually occurs in regions with long PSTN setup times and suggests raising the failover timer to 20 seconds in those regions or on all Direct Routing trunks.
Checked 2026-10-02
- Vendor
- Microsoft
- Product
- Teams Direct Routing
- Subsystem
- SBC configuration
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- current as of 2026-10-02
- Checked
- 2026-10-02
Sources
- SIP 408 and Microsoft response codes - Microsoft Teams — Microsoft · tier 2 current vendor documentation · Section '500001 408 Gateway (SBC) failover timer expired'
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting SIP 408 Request Timeout and calls that get no response: source note sip-408-timeout-troubleshooting-ms-failover-timer-20s-advice. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-408-timeout-troubleshooting-ms-failover-timer-20s-advice
BibTeX
@misc{warmtransfer-claim-sip-408-timeout-troubleshooting-ms-failover-timer-20s-advice,
title = {Troubleshooting SIP 408 Request Timeout and calls that get no response: source note sip-408-timeout-troubleshooting-ms-failover-timer-20s-advice},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-408-timeout-troubleshooting-ms-failover-timer-20s-advice},
note = {Source note sip-408-timeout-troubleshooting-ms-failover-timer-20s-advice, checked 2026-10-02}
}