I remember that every time I bought a new Android phone, there was a new chat app that was - obviously - not backwards-compatible with the previous one. Some of

I remember that every time I bought a new Android phone, there was a new chat app that was - obviously - not backwards-compatible with the previous one. Some of the contacts were usually there, some random ones from my Gmail account appeared too. All chat history was gone. Some of my friends used Hangouts a few times - it was working reasonably well, and Gmail integration didn't hurt either. Granted after a few "iterations" of Google messaging apps, no one I know uses them, ever.