Futel.net

Futel is half hacker project and half public good. At it's core, it's a literal payphone that anyone can use, for free, to make outgoing calls, as well as leverage free voicemail services. Beyond that, it's also a zine documenting its usage, an incoming number to hear all sorts of audio ephemera. In short, a fascinating series of phone interfaces that also provide services that may be critical for those in need.

You can read more about the project on their site and blog or spend a few minutes with this YouTube presentation that walks through all of it.