iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone X (GSM), released on 2019-01-22T18:09:24Z. The update package is 286.06 MB. This is a delta (partial) update that requires 12.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b86f28036da7ec169539818d8a48c747c7a4972a.zip.