Hey everyone, I’ve run into a really strange issue with SIP trunk connectivity during high-concurrency load testing.
Background
Environment is US1. Using JMeter 5.6 to simulate inbound SIP traffic. Targeting Genesys Cloud PSTN trunk. SDK version 2.3.0 not used here, direct SIP.
Issue
At 50 concurrent calls, 10% of INVITE requests return 503 Service Unavailable. No specific error message in SIP response body.
Troubleshooting
Checked trunk status in Admin. Status is ‘Active’. Verified call capacity limits. No obvious rate limiting headers in SIP response. Is there a hidden SIP connection limit per trunk?