Hi, I have a Galaxy S4 i9505 running on 4.4.2. I have two phone numbers. One for me and one for my husband. I want to contract the Galaxy S5 and give my husband the S4. This means swapping the sim cards. My provider says I have to cash out the S4 which is expensive. The phone is only 4 months into a one year warranty. I don't want to void the warranty either. One solution is to unlock both phones and to relock if there is a problem and I need to bring the phone to the dealer. Can I do this?