iOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone 7 (GSM), released on 2018-04-24T17:11:34Z. The update package is 841.19 MB. This is a delta (partial) update that requires 11.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 66c0ef8bb28b957a05deaa369986626789b80b8d.zip.