[andy]

I'm not quite following this. Do you mean you are using two phones, one to trigger callback on the other?

I'm not aware that a Kuwait number would incur incoming charges for international-sourced calls, but if so others can comment on that. If you mean that the phone receiving the call is from another country, then an incoming roaming charge would be incurred whatever the source of the call to it. Unless you get a global SIM with free incoming calls

But perhaps I've misunderstood the question ...