Only iPhones can use iMessage. iMessage uses a data connection rather than SMS or calling. OP lives in a different country and international SMS or calling would cost a lot of money, but a data connection does not. The only way of communicating with certain people without incurring extra charges is for OP to use iMessage over a data connection.
What does that have to do with the phone they own? I still don’t get it.
Only iPhones can use iMessage. iMessage uses a data connection rather than SMS or calling. OP lives in a different country and international SMS or calling would cost a lot of money, but a data connection does not. The only way of communicating with certain people without incurring extra charges is for OP to use iMessage over a data connection.