Could someone clarify why the Outbound Dialer API returns 429 Too Many Requests when simulating 50 concurrent calls? The goal is to validate contact list import throughput.
The error spikes immediately after 10 requests. Is there a specific header or configuration needed for high-concurrency imports?
TL;DR: Implement exponential backoff in JMeter.
This is caused by the platform’s burst limit enforcement. The 100 req/min rate applies per tenant, not per connection. The Outbound API enforces strict burst caps, so sending 50 concurrent requests triggers immediate throttling. Use the Retry-After header value to space requests. JMeter’s Constant Throughput Timer helps distribute load smoothly.
Pretty sure the outbound dialer enforces stricter burst limits than standard REST endpoints. The suggestion above about exponential backoff is correct, but ensure your JMeter script parses the Retry-After header dynamically. Hardcoded delays often fail under variable load.
"Retry-After": 3