In May this year, Google in their infinite wisdom has migrated everyone using Google Talk (baked into Android since day dot) over to the Hangouts app. There’s a problem with this: Hangouts is not XMPP compatible and is not federated with the rest of the XMPP network. Here’s a quick breakdown of what this means:

• Google Talk app can message to Hangouts and all XMPP contacts.
• XMPP apps (like PSI, Miranda, Xabber, Empathy etc) can log into Google Talk service and then message Hangouts and all XMPP contacts.
• XMPP apps logging in to other servers (jabber.org, jaim.at etc) can message all XMPP contacts including Google Talk but NOT Hangouts.
• Hangouts users can message ONLY to Hangouts and Google Talk service users.
• Theres no way that I can see for telling which of Google Talk or Hangouts a  *@gmail.com contact is using.

This is of course incredibly disappointing for anyone who relies on XMPP instant messaging and uses a server other than Google’s, as most regular users on Android phones are of course using whatever Google makes available to them (ie Hangouts) and are now cut off from the rest of the XMPP network. This amounts to about a third of my contacts. So much for interoperability, Google.

Recommendations for gmail.com users:

• If you connect to Google Talk server using an XMPP client (like the “Talk” app on Android) rather than the Hangouts app, you’ll have connectivity with Hangouts users as well as XMPP network users, as per usual.  There are plenty of other good XMPP clients; I’ve tried xabber on Android and it works nicely. PSI is a great client for desktop Windows/Linux/Mac. Mac supports XMPP through iChat, and most Linux distros include XMPP support in their default desktop environment.
• Google Talk the XMPP app is now discontinued, but Google has made no announcement that it will discontinue the service itself. You may wish to consider what happens if they ever do. I for one am predicting it’s demise and jumping off the Google ship as of today.