It depends entirely on where you are from and what kind of mobile plan you have. Check out your mobile provider`s international plans. If you don’ t like suggested options, then you have a couple of options. The first is to keep your phone in an airplane mode and to only use Wi-Fi. The second is to unlock your phone and buy SIM cards in new countries. The key tip is to make sure that you do not use mobile data abroad without an international plan or a new SIM card as it will be very expensive.