That old blog post has long vanished in a redesign of his site, but not long ago he replaced it with a new version called simply P2P SIP URI Dialing. It’s a good reference on the subject. Highly recommended.
Of course, dialing by SIP URI is really about wholly bypassing legacy telcos and what remains of their TDM networks. It assures that you have IP connectivity between end-points. That simple fact is what opens up the opportunity for wideband calling (HDVoice) as well as video calling and even encrypted calling.