I emailed ST about a 10 days ago re: iphone 3s being used. They said new program BYOP. Went to Walmart and they said that they can't use my phone because it's ATT service and I have to have their permission. I am not under a contract with ATT and I bought the phone from Apple so why can't I use it. I don't want to invest in an iphone 5 until I see how the coverage in my area is. I am not familiar with ST. Why can't I us my current phone?