I've seen so many threads on putting another SIM card in another phone. Yes, sometimes it will work. DON'T!!! This WILL VOID the manufacturer's warranty. My finance and several others I know have had this happen. Just not with AT&T phones, plans and GoPhones. Verizon, T-Mobile and others too. Please do not swap SIM cards. It'll save you money if your phone has a warranty. Not sure? Call your carrier's tech support. They will be able to tell you.