I will be travelling to Italy in Set./18. I have an un-locked iPhone and am on pay as you go with Koodo. Is an international pre-paid SIM the cheapest option? I assume iMessage would still work with 'Data' turned off. Is this correct? Can I just order a SIM card from any company and assume it will work when I get there or is there a way to test Sim in phone while still in Canada? Thanks.