For those of us who are aware that these things exist, but now how they all integrate: how do you go from SIP server to actual phone service?

Are you meaning that the SIP server is shared by all the friends in the network who want to talk to each other, or that you can get phone service via the SIP server?

My dad worked on a lot of VOIP equipment in his career, so I always kind of wanted to do this, but don't like the $10/month for something almost never used, and got my kid a phone anyway because the portability and camera are pretty key. We just control the phone so that it acts like a land-line. I might be templated to do a VOIP setup for the house any if were easy enough.