iOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPhone 5s (Global), released on 2018-03-29T17:12:10Z. The update package is 666.33 MB. This is a delta (partial) update that requires 11.2.6 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 3f7cf96a868d1b94112222998d4e4da6fe3abeb5.zip.