One of the most frequently asked questions was whether it is possible to upgrade to the final version iOS 9, which will be released today, through the OTA installed iOS 9 GM or iOS 9 public beta ?
iOS 9 GM / iOS 9public beta
Last week Apple released iOS 9 GM or Golden Master with build 13A340 to developers. Golden Master is the final build of the firmware iOS 9, which is released before the official release. Developers use it to represent their applications for iOS 9 in App Store.
Most likely, today's release will have the same build number as iOS 9 GM until Apple finds and fixes a critical bug.
If the final build number iOS 9 changes, you will receive an OTA update. However, if the final build number iOS 9 is 13A340, the same as iOS 9 GM, then you don't need to do anything.
If you are still on iOS 9 Beta 5 or below, you will also receive an OTA update after iOS 9 is released today.