Predictive Dialer 503s on AP-Southeast-1 BYOC Trunks

Outbound predictive campaigns are failing with SIP 503 Service Unavailable specifically on our AP-Southeast-1 BYOC trunks, despite inbound traffic flowing correctly on the same ports.

Does anyone know if the predictive routing engine respects the carrier-specific failover logic defined in the trunk settings, or does it require a separate timeout configuration in the campaign profile?