Trying to understand the failure mode when pushing our Genesys Cloud SIP trunk to 120 concurrent sessions via JMeter. The environment is Singapore. Requests start failing with SIP/2.0 503 Service Unavailable after roughly 45 seconds. The WebSocket connection remains stable, but the media path drops. What is the specific concurrent session limit for a standard SIP trunk before 503s trigger?
Check your JMeter thread group configuration for pacing issues.
- Set a constant timer to 500ms between requests.
- Reduce concurrent threads to 80 initially.
The 503 error usually hits because the burst rate exceeds the trunk’s admission control limit, not the total session cap.
Check your SIP trunk configuration for admission control thresholds, as the default burst limit is often lower than the sustained capacity. The documentation specifies that exceeding the initial burst triggers a 503 before the steady-state limit is reached. See SIP Trunk Configuration Docs.