............? I am wondering if I can use another service provider for a calling plan,such as verizon.Can anyone help?

Your phone may be locked to a specific provider. You must get it unlocked to use it on another network

I don't think Verizon will let you use your US Cellular phone with one of their plans. I know that US Cellular doesn't allow phones that aren't US Cellular branded phones on their plans.

It's a shame that CDMA doesn't have SIM cards. This is one benefit of GSM. (Though I have found fewer dead spots with my wife's US Cellular phone than with my phones on Cingular and T-Mobile.)