iOS 9.3 (build 13E5231a) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2016-03-07T17:48:51Z. The update package is 34.15 MB. This is a delta (partial) update that requires 9.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 181c2009ffc604042ab14b733400e7fce949e04a.zip.