iOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPhone 5s (Global), released on 2018-03-29T17:12:08Z. The update package is 761.39 MB. This is a delta (partial) update that requires 11.0.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 4b2a8f5bbede599b6f8d4fdaae040c7674448e02.zip.