I think there were two major technical issues stopping the overwhelming adoption of mobile XMPP/Jabber: 1) Apple push notifications were the only method of rel

I think there were two major technical issues stopping the overwhelming adoption of mobile XMPP/Jabber: 1) Apple push notifications were the only method of reliably delivering on demand messages to iOS devices, so to provide expected (app in background) behavior on iOS, someone had to provide an always on proxy between XMPP and iOS push notifications, and that proxy had to have your credentials. This required ongoing expense on the server side combined with a client side app. 2) XMPP is connection oriented and doesn't handle the disruption of disconnections and changing IPs/networks when a mobile device roams or transitions from wifi to cellular data. On the political side, I think GTalk had, by far, the largest network of XMPP users. As I understand it, they've tried to solve some of these problems with proprietary protocol changes which resulted in the Hangouts app and the subsequent dropping of full XMPP support by google: https://www.eff.org/deeplinks/2013/05/google-abandons-open-standards-instant-messaging https://www.eff.org/deeplinks/2013/05/google-abandons-open-s...