Predictive Dialer 429s during JMeter load test on US1

Quick question about rate limiting on outbound campaigns. Running JMeter 5.6 with 30 concurrent threads against POST /api/v2/dialer/campaigns to validate throughput. Getting immediate 429 Too Many Requests errors after 5 seconds. Environment is US1. Config seems standard. Is there a hidden limit for campaign updates per minute? How to bypass this rate limit during load testing?