Been having issues with data and AT&T after the latest 8.4 update. Cant send MMS (gets stuck and then says unable to send), Siri says can't connect to internet. Cant send Share My Location to others. Meanwhile, i am able to check mail, load up safari, etc. Edited; Just got off the phone with AT&T, said its an Apple and iOS 8.4 issue with network and servers, they are aware and working on a fix.