I will be vacationing to London, Paris, Venice and Rome in a month. I have been looking for the best SIM card to use when traveling. I am a bit confused with how roaming works. Is there one SIM card I can purchase that will work with the counties I am going too and will that be economically viable, or will it make more sense for me to purchase a separate SIM card in each country. Any help and advice is greatly appreciated!!!!
EDIT: I have an unlocked phone
Any suggestions of plans will be great as well!