We used Virgin Mobile for a few years before we got our smarter than us phones.
Started with the thumb drive then went to the overdrive pro so Mom and kids could connect too. The only place I had difficulty using it was at the North Carolina Welcome center. But they had their own wifi at the time and I think it may have had something to do with that.
With it you buy what you need each month and at the end of that month you can buy more or do nothing. I think you have to use it at least once a year to keep the account activated. I never went over on my data with it. Still got them somewhere.
