Hey Nikhil. What you're describing there probably isn't achievable. Picking those 4 countries and having accurate mobile coverage and spam protection is an expensive problem to solve.
In case you're looking for unsolicited advice, I'd pick just one target country. Pick a good quality data provider like Fullenrich. Then dial your phone over and over and keep going until you get traction.
Once you've got good traction and paying customers, that's when you should try to solve the other points - if you still think they're problems at that point.
