Comment by toast0

Which countries? Where I live, in the US, if you want to make a callback to a police detective, you have to call 911 and ask to be transfered. It's clearly not an emergency, and the detective will tell you to do it. This police department doesn't have a phone system that allows the public to call a non-emergency number and have their calls routed.

But most places I've lived in the US had a non-emergency police number, and non-emergency 911 calls were very discouraged. If you have a good reason to make them for network or device testing, you'd just need to schedule a time to make a test call, stay on the line and tell the operator, etc.

Device development would be well served by using a tower simulator in a Faraday cage, as a sibling suggested. But a responsible developer would do a few tests on live networks during release acceptance testing.