Some klind of cell phone trick... does it work?

i have the LG Lotus from sprint, and it's so crappy. I've had it for a year and can't stand it, it's horrible. Just recently a friend of mine told me you could buy used ones or take someone ele's old phone, even if it's from another network, and dial some kind of number and it'll work. I would totally do that, if it works. Anyone ever tried it??