iOS 12.1.3 (build 16D5039a) is an official Apple over-the-air update for the iPhone 8 (Global), released on 2019-01-10T18:08:54Z. The update package is 56.17 MB. This is a delta (partial) update that requires 12.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c2fcb87f4e77231d7a3a52e8b4d6a62cf028d4a3.zip.