The phone boxes were successfully killed off here in Poland in last 15 years; most likely because mobile networks become more reliable, dense and cheaper. Devices in particular places like hospitals or prisons should be still running and supported, as acc. to wikipedia article it's required by law but since the national telecom was privatized (now mainly owned by Orange) no official service provider was designated for the task.

Last time I had chance to use a phone box I didn't even call - I had to text someone to actually call me on my prepaid phone.