Is that sarcasm? Because even with it was using XMPP, Google Voice broke constantly due to their updates and changes. People were hitting this forum and the IRC room constantly with “GV down for anyone else?”. This guide was posted four months ago, this is now the 3rd change that has broken how it works from Google. That so far as been par for the course.
However, what I do find interesting about this is the fact that the only changes that are breaking connections are the URI’s. Especially since both the new chirp.telephony.goog URI is resolving to the exact same IP that obihai.telephony.goog still resolves to. Granted the voice.telephony.goog is resolving to a different IP but that doesn’t automatically mean it is a “different” system.
So a pretty good theory here is that they are changing their domains to do exactly what is has been doing. Breaking things like this.