SIP Trunk 408 Request Timeout at 100 concurrent calls Singapore

Need some help troubleshooting SIP 408 Request Timeout errors when ramping JMeter 5.6.2 to 100 concurrent outbound calls from Singapore.

Single calls connect fine to the Genesys Cloud SIP trunk. The timeout hits immediately once concurrency exceeds 50.

Is there a default session limit per tenant in the Asia region?