A:Answer The phone, whichever you use, must be AT&T Compatible, an Open Phone (meaning: it was unlocked, so to be used with most carriers); or it must be AT&T issued phone. A GoPhone will work too. If you have another phone carrier, check their "No Contract Plans" ... Most carriers have them, & some may even give you a free phone; probably outdated, but free still! ;*) If you have to travel overseas, check with a Carrier directly, to see what best option they have. Do not oay oer use, though. It gets very expensive quickly; in the hundrends, if not more!!! I recommend you get a simple plan with internet options, so you can csll voa Skype, Tango, or any other Call/Video App. That can save you $$, if your internet is inlimited, & or if you don't go over limiys.