Is it possible to turn off SMS for certain countries / stages in recruitment process

We are implementing 2 Way SMS messaging for client who are global. However, they do not want to turn on two way messaging across the whole world:

Is it possible in any capacity to turn off SMS messaging for the whole journey and only activate it for specific parts, such as interview reminder, good luck message before assessment centre, urgent update.

If you buy a package with a SMS provider only for certain countries, what happens if an out of scope country candidate inputs their phone number (i.e. will they receive SMS messages)

Is there a way to turn this functionality off for certain countries where this functionality isn’t available