Experiencing intermittent SIP 403 Forbidden errors when traffic fails over from the primary Singapore BYOC trunk to the secondary link in the AP-SYD region. The primary trunk maintains stable registration and handles outbound calls without issue. However, when the primary link drops or is manually disabled for testing, the Architect flow routes to the secondary trunk, and registration fails immediately with a 403.
Credentials are identical across both trunks, and the SIP domain matches the carrier’s requirements. The error occurs within the first 30 seconds of attempting re-registration. Has anyone encountered carrier-specific quirks where the secondary trunk is blocked due to IP reputation or rate limiting during failover events?
Environment details: Genesys Cloud BYOC, AP-SYD edge nodes, Terraform-managed trunk configuration. The issue persists across multiple carriers, suggesting it might be related to how Genesys handles the handshake sequence for secondary endpoints. Any insights into the underlying failover logic or carrier-side restrictions would be appreciated.
While this is a SIP routing issue, not a recording export one, the 403 error during failover often stems from certificate or credential synchronization delays between regions. In my experience with BYOC edges in London, the secondary trunk sometimes holds stale session tokens when the primary drops unexpectedly.
Check if the secondary trunk in AP-SYD has a valid TLS certificate that matches the primary. Even if credentials are identical, the certificate thumbprint must match what the Genesys Cloud edge expects. If you are using BYOC, ensure the certificate_id in the trunk configuration is explicitly pinned and not relying on auto-rotation, which can cause drift during failover events.
Also, verify the SIP domain configuration on the secondary trunk. Sometimes, the domain resolves to a different IP range in the secondary region, and the edge firewall blocks the registration request as unauthorized. You can test this by forcing a registration refresh on the secondary trunk via the API:
POST /api/v2/communications/trunks/{trunkId}/registrations/refresh
If the refresh fails with 403, the issue is likely at the network or certificate level. Check the edge logs for TLS handshake failures. If the handshake succeeds but registration fails, look for credential mismatches in the audit trail.
Another common fix is to ensure the secondary trunk is pre-registered. If the secondary trunk is not actively registered before failover, the initial registration attempt might be throttled or blocked by rate limits. Configure the secondary trunk to maintain a warm standby state with periodic registration pings. This ensures the registration is valid when the primary trunk drops.
Finally, check the IAM policies if you are using S3 integration for recording exports, as a 403 error can sometimes be misreported from downstream services. However, in this case, the SIP 403 is likely due to certificate or domain mismatch. Pin the certificate ID and ensure the domain is consistent across both trunks.
The suggestion about certificate synchronization is a good starting point, but from a load testing perspective, the 403 often indicates a mismatch in the SIP registrar configuration rather than just TLS. When switching trunks, ensure the secondary trunk in AP-SYD has the exact same IP allow-listing and port configurations as the primary.
In JMeter, I usually simulate this by forcing the Via header to match the secondary trunk’s public IP. If the Genesys edge sees a different source IP than registered, it rejects with 403.
Check the Genesys Cloud Admin > Telephony > Trunks settings. Verify that the “SIP Domain” and “Transport Type” are identical. Also, look at the SIP trace in Genesys. If the INVITE goes to the wrong registrar IP, it fails.
Try restarting the BYOC edge service for the secondary trunk to force a fresh registration. This clears any stale session states. Monitor the 500ms latency between registration and call attempt. If the failover takes longer than the keep-alive timeout, the connection drops before the call is established.