Thanks to you both for your replies. Got the Obi set up and based on a couple of short test calls it seems to be working just fine.
I noticed the threads a while back about how to use your phone wiring, but not sure it's worth the trouble. If I understand correctly, I can use a cordless phone with a base unit and a bunch of satellites without going to as much work and pretty much get the same result. Maybe I'm missing something.
I'll test it for a while and more than likely ditch the Comcast voice service. This is cool!