I just use cricket. I get a cheap Android, pay a fair price for the abuse I put my phone through, and there's no contract. Because when you know you'll be a few days late with every payment just about because you're a jobless bum, you don't want any contracts attached to your cheap piece of crap.
Holy shit. Someone find me a job.
But in regards to pay phone use, there are only a handful scattered around within 20 miles of me. Mostly one at a gas station, or the occasional 7/11 may have one still. If it's functioning and in one piece, that's another story all together. Most of the time though the only people who use them tend to be fucked in the worst way possible. Cell has died, can't charge the battery, and the car broke down.