AT&T is pushing the Android 4.4.4 KitKat update for Samsung Galaxy Note 3 users. This new update will move your Note 3 software from Android 4.4.2 to 4.4.4.
This is a huge 459 MB OTA update, which brings in some new feature like Knox 2.0, Kid Mode, SideSync 3.0, and virtual tour mode in camera app. Also, you will expect some new AT&T apps, which you may never use in your lifetime.
After updating this software your Galaxy Note 3 will show the build number as N900AUCUDNJ5.
This is OTA update, so you may have already got the notification to update your Galaxy Note 3. If not, either you can wait some more or just check manually by going to Settings → More→ About Device → Software Update → Check for updates.