Did you know that we run a pretty sweet Asterisk server in Fedora Infrastructure? It's simple to connect to it via nearly any SIP client. When i mean nearly any, this means not just your computer, but your SIP phone, your Android, your Maemo, and pretty much any device with a speaker and microphone that lets you run your own software. There are also dial in numbers so you can reach the system from some countries, like the US. You can even use it to have friendly chats with other Fedora contributors without racking up expensive long distance phone bills. It's not just there to look pretty, but it's really part of the Friends bit of Fedora. (And well, it's also free, full of features, and i don't know of any other open source community offhand that has Asterisk set up.)
My thanks to Fedora Infrastructure for the great job they do and all the hard work.