Can they order pizza with these phones?
Though on a serious note if you look over some of the stories involving use of public payphones in larger American prisons and the dangers associated with them I can't help but wonder if this isn't a half bad idea. From the stories I've heard, no way to verify them either, many public phones in American prisons are under the control of various gangs.
This might go along way in reducing butt rape incidents in the shower over making a call to grandma on her birthday.