There is the ability to disable international calling completely. That is how I have things configured for the test accounts. I would be inclined to soft launch my Reseller Account without outbound international calling - I do not see it in my demographic. (Realistic or not.)

When International calling is not permitted, can the Control Panel remove the "Block International Calls", "Allow International Calls" from the Features page?

https://cp.voipwelcome.com/features

Do you have any stats on how popular international calling is for VOIPo?
Is it say, 50% of the customer base?

On my VOIPo account, I keep it at "Block International Calls".