im new here this is my first post . i had this thought for quite awhile and had no idea how to search for it without typing a paragraph.. so here it goes . i have a galaxy s3 (sprint) and i want a new phone but i dont want to have to upgrade so my question is if i bought a gs4 for example from ebay (for sprint id assume it would have to be) and id put my sim card in it would it be able to replace my s3 without having to pay an upgrade fee? because i then wanted to give my gs3 to my brother and figured the swapping of sims would still work. thank you for the help.