iOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPhone X (GSM), released on 2018-03-29T17:11:35Z. The update package is 676.06 MB. This is a delta (partial) update that requires 11.2.5 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 1e189d0c4a3a3df3f899e6531c61858912517540.zip.