I use Virgin prepaid mobile as well, Mike. Very happy with it. They purchase time from Sprint PCS.

And actually, you only have to add time every two months. $20 minimum. No monthly fee. Makes for a very inexpensive phone service for those who only use it when they travel. Also, calls to anywhere in the US are charged at the same rate as local calls. You can choose to have your phone number in any area code you desire to minimize charges to those calling you frequently from a particular city.