Microsoft Lync might be the way to go as it's supported on all 3 platforms. Apple, Computer, iPhone, iPads, Android Phone / Tablets, and Windows Phone / Tablets / Computers.

I am having a terrible time getting this working... Do I have to remove the existing AD connections before I setup and sync my ADAM connection?Also If I delete my existing AD connection, then try ADAM and it fails, can I then go back and re-add my AD...