Longman Dictionary of Contemporary English
pay phone
noun
EXAMPLES FROM CORPUS
▪ It wasn't permitted to take incoming calls on the pay phone in the hallway of the hotel.
▪ Radio journalists learned to carry lots of change because a pay phone was a necessity when a story was breaking.
▪ The closest one she can find is a pay phone just outside Mac Court.
▪ There was a pay phone on the wall next to the hall stand.
▪ When Lucy came out, Josie was on the pay phone at the corridor's end.
Wiktionary
pay phone
n. (alternative form of payphone English)