Outbound Dialing API 429s on low JMeter concurrency

Could someone clarify why the Outbound Dialing API returns 429 errors immediately? Running JMeter 5.6.2 with just 5 threads against Genesys Cloud BYOC Edge 24.1.0 in Asia/Singapore.

Testing the predictive dialer capacity planning endpoints. Getting HTTP/1.1 429 Too Many Requests instantly.

Is there a specific rate limit for outbound campaigns I am missing? The docs mention general limits but nothing specific for dialing throughput at this low scale.