quick question about outbound dialing failing in us-east-1. getting 503 service unavailable on POST /api/v2/outbound/calls when jmeter hits 50 concurrent threads. the architect flow is simple just a play message but it fails after 10 seconds. any ideas why?
You need to check your BYOC trunk capacity and carrier-specific rate limits immediately. A 503 Service Unavailable on the outbound API usually indicates that the underlying SIP trunk has hit its concurrent session limit or the carrier is rejecting rapid-fire INVITE requests. With 15 trunks managed across regions, it is easy to overlook a specific trunk’s max concurrency setting in the Genesys Cloud admin console. Verify the “Max Concurrent Calls” setting for the specific trunk assigned to this dialer campaign. If that is sufficient, the issue is likely carrier-side throttling. Many carriers enforce a gradual ramp-up for outbound calls to prevent fraud flags. Check the SIP registration status for that specific trunk to ensure it is healthy. Refer to the official documentation on BYOC trunk configuration and carrier failover logic at https://help.genesys.cloud/article/btoc-trunk-config. Adjusting the dialer’s “Predictive Ratio” or adding a slight delay between call attempts often resolves this saturation issue.
Take a look at at your outbound campaign pacing settings. The suggestion above covers trunk capacity, but Genesys Cloud often enforces a “Rings Per Second” limit within the campaign configuration itself. If your dialer is firing faster than the platform allows for that specific strategy, it will throttle requests regardless of trunk health.
Note: Check the “Max Concurrent Calls” in the campaign settings, not just the trunk.