I use Virgin Mobile - minimum of $20/3mo to keep it active, and minutes cheap enough that I've never paid more than that. Their phones use one of the major networks, either Verizon or AT&T, I can't remember which. The cheap little Kyocera phone I bought has good voice quality, cost like $60, and the battery lasts almost a week without charging. My only customer service experiences, both human and automated, have been positive.