iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone X (GSM), released on 2019-01-22T18:09:25Z. The update package is 287.46 MB. This is a delta (partial) update that requires 12.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 58d5942b484b48132a6b93e6b77f0831684d61be.zip.