Unfortunately it won't work. Unlocked or not. AT&T is a GSM network carrier, while US Cellular is a CDMA network one. They aren't interchangeable and a phone can't be converted from one to the other. You would either need to get another GSM carrier to use the phone on, or get a new phone from a CDMA carrier.
Unfortunately it won't work. Unlocked or not. AT&T is a GSM network carrier, while US Cellular is a CDMA network one. They aren't interchangeable and a phone can't be converted from one to the other. You would either need to get another GSM carrier to use the phone on, or get a new phone from a CDMA carrier.