That can be fun, but watch out. If your school is very intrusive (like mine was) they'll start watching you more closely when they see you hanging out at the payphone at school (assuming you're talking about high school). If it's something on campus for college, then knock yourself out. You'd be stupid not to do it.
Speaking of, does anyone know the new # for BT services? Or, at least, one that can be dailed from a payphone, or if the company even still exists? Someone should know... hopefully.