Forgetting to Set Your Data roaming. PLEASE do not forget to set up your mobile phone before you leave to avoid international data roaming charges. They are ridiculously expensive. Check what plan you are on, some may have inclusions but most will not so just ensure you are covered! If you have no idea what data roaming is, it means that your phone is using a mobile network that your mobile operator doesn’t own to send and receive data. Your mobile operator will charge you extra for data roaming, and this service must be available with your current phone plan- if not, they charge you up to triple for every single internet page, text or call!!