Amazon Connect - calling Toll free number - error : call can not be reached.

by default the Active Concurrent Calls limit for the instance was 1 leading to the behavior being observed. raise a case then the internal team will enhanced the Active Concurrent Calls limit to 10 and has recommended to test the same at your end. Thus, to further enhance the limits you may create a "Service Limit Increase" support case directly via the AWS Support Center using the following link:

[+] https://eu-central-1.console.aws.amazon.com/servicequotas/home/services/connect/quotas/L-12AB7C57