Board Thread:User Wiki Issue Reports/@comment-68.150.48.218-20140308062827/@comment-27862737-20170921161720

If you're an iOS player, you cannot add Android players to your friends list - they are on a different server entirely. Also, if you're a Global player, you cannot add EU players to your friends list either.

Also, this thread is originally from 2014/2015. VERY old.