"This VoIP engineer" got as far as you (one way audio), and gave up. I find it easier with the Skype client, and being able to use my cell phone's number as the caller ID, just make life easier. I can live with the $3/mo to get unlimited calling added to my $29/mo 500 minute plan.

I also tried getting sipgate working with some other trunk services I have, to no avail. However I haven't tried since the latest update(s). Whenever I get a free "weekend" to waste, I may revisit.

Good luck with that though.