iOS 12.1.2 (build 16C101) is an official Apple over-the-air update for the iPhone X (GSM), released on 2018-12-17T21:06:15Z. The update package is 1.65 GB. This is a delta (partial) update that requires 11.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f9285c6bbb62616f5492ae85fb3fac765bf697b2.zip.