Using ALLTEL phone with US Cellular service

I called US Cellular and told them that I was getting another phone because my current one is damaged. I was told that I could use the phone, although I informed the rep that the phone would be under a different service. The male said it wouldn't be a problem. I had my aunt 'next day' the phone. I called US cellular and was informed that I couldn't do it. I was pretty ticked off. Do you know how much UPS charges for next day delivery? Almost as much as it costs to get a refurbished phone from my insurance. BTW I've gotten 4 from insurance since last Xmas. Thats too much.