I have a motorola moto g xt1039 unlocked phone. I want to activate the phone and then find a service plan. Can I buy a sim card starter kit and then use $10 refill cards. I was looking at T-Mobile and at & t. Does that sound right? I have never owned a smart phone and bought this one for myself and others to use over seas. We just need it state side a week before and a week after our trip.