Building your own PBX

Building your own PBX: "What would it mean to you to have your own full-featured PBX system at your home or small office? What would it mean to you if you could build an entire PBX system (minus the phones) on hardware you probably have laying around, AND that it can probably also save you money on your phone bill? Sounds too hard to believe doesn't it, but using old hardware and some open source software, you really can build a commercial quality phone system that would normally cost thousands of dollars."