I traveled to Paris and London for a month without a phone but has been hard without calling on the go. Next month I'm heading over there again so is there any way to use my iPhone 6 over there? I hear unlock is one way and buy a SIM card but I don't know much about it and what the process is. Is there a better way or just find a burner phone there? I currently have a AT&T grandfathered unlimited data plan if helps anything.