Can anyone explain why the SIP trunk returns a 408 Request Timeout error when scaling concurrent sessions beyond 40 threads in JMeter 5.6? The load test targets the Genesys Cloud US1 environment. The script initiates SIP INVITE requests to the Genesys Cloud SIP endpoint. When thread count is below 40, calls connect successfully. At 40 threads, the timeout errors start appearing. The error response is: 408 Request Timeout. The SIP logs show the INVITE is sent, but no 100 Trying or 200 OK is received within the timeout period. The environment uses standard SIP trunking configuration. No firewall issues are detected. The JMeter test plan uses the HTTP Request sampler with SIP protocol support. The goal is to validate call capacity and identify bottlenecks. The documentation on SIP trunking limits is not clear on concurrent call limits. Genesys Docs. Any insights on the cause or workaround would be appreciated. The issue is consistent across multiple test runs. The JMeter server has sufficient resources. The Genesys Cloud org has adequate capacity. The problem seems related to the SIP signaling path.