AT&T is in no mood to release Windows Phone 8107 software update as one of the AT&T community manager confirmed on community forum by saying
I got some news about the Windows Phone 8107 update and wanted to share it with you all.
We are not currently planning to offer the Windows 8107 update.
I don’t have any additional information right now. If and when I get details, I will update the thread.
It comes as surprise that AT&T won’t push 8107 update which fixes various issues, including the most famous "keyboard bug". Keep an eye on community as wireless carrier will provide some additional information on that matter in near future may be they will change their mind.
Source:- AT&T Windows Phone Community