iOS 9.3.1 (build 13E238) is an official Apple over-the-air update for the iPhone 5 (GSM), released on 2016-03-31T16:54:40Z. The update package is 254.99 MB. This is a delta (partial) update that requires 9.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 074f9460ac4dfed449f7b738c46ab32842306d93.zip.