Hello, going to America shortly and although I intend to watch my children like hawks I’d like some way of tracking their location should the worse happen and we get separated. My eldest has a mobile on o2 I have a spare old iPhone that i could get another sim for for my youngest to carry but does o2 work in the USA? Would pay as you go work or would it have to be pay monthly, and how to I ensure I don’t get charged a fortune for roaming?