Payphones are expensive to maintain, with diminished usage I can understand why they are disappearing; BUT they still come in handy
(especially in areas like bus terminals, airports, subways).
In my post #1, I did find a pp in the 8th Ave. subway concourse!
[Not all cellphones work internationally, so a tourist from (say) France couldn't use his cp in the USA. I can't use my cp outside the USA. I can always tell when someone is calling from a cp = choppy transmission
]
The vast majority of foreign cellphones will work just fine in the US (and vice versa). There might be roaming charges (dollar or two a minute, if you don't have a plan), but they'll work.