A group of telephony hobbyists who restore and maintain old equipment. They figure out how to get their gear VoIP-enabled and built their own PSTN on top of the Net by hooking everything together. It's pretty serious, plus they document their work pretty well.

Introduced at The Last HOPE, this online project is a recreation of yesteryear using open source software. Phiber Optik used a modified build of Asterisk to build a virtual telephone network that you can hack around with using a blue box (or a software emulation thereof). It's completely isolated and completely legal, and was built for those of us who got into phreaking after electromechanical switching disappeared. If you want, you can set your own instance up by downloading the patches for the software.