We’ve purchased a few “unlocked” phones from Craigslist & Ebay – and here’s been our experience – albeit with TMobile & AT&T:
- As long as you aren’t under contract w/ a particular device and/or don’t require a new data plan to support your newly purchased phone (which means you are making NO changes to your services, just moving the number to a new device) there should be no expense.
- You may need a new SIM card if your current phone’s SIM card cannot fit into the new the phone. (Many newer phones have smaller and smaller micro SIM cards). If you need a new micro SIM sometimes your phone company may attempt to charge for the new SIM. In our case T-Mobile did not charge us. If there IS a charge, there are often tools you can purchase online (like this one) to trim down your old SIM card all on your own.
Also, Ebay has a helpful page explaning some of this info.. You might want to read that link, too.
..AH, and last and most importantly.. I see you’ll be very constrained because US Cellular is a CDMA network—so I don’t think it’s possible for you to add a non-supported device to their network.
Info on all networks and carriers here.
If I were in your shoes (and if you plan to continue to stay with US Cellular) I would call them first before making a purchase of a new phone to make sure it would be possible to use it on their network.