I bought a phone of amazon and I just received it and it came with a paper that said stop to activate phone please read and it sais I need to put the sim card amazon provided to activate the phone but it didn't come with a sim card so I just put the simcard from my old phone and it works just fine I can make call text ect. So my question is it already activated? Do I need to still activate the phone even tho I can make calls on it? By the way I upgraded my att phone from a 2 year contract that expired