TexasCHLforum.com

I have used TracFone in the past. It's an established MVNO and has arrangements with the big US carriers, not just AT&T. Whose network you get depends on the phone you buy.

It sounds like your friend is on a prepaid per-minute plan which is quite economical for low usage. There are even more frugal options in the MVNO space, but not off the shelf at Target & Walmart. For light users, TracFone service can be had for less than $100/year, which is cheap enough for many.