iOS 9.3.1 (build 13E6238) is an official Apple over-the-air update for the iPhone 4s, released on 2016-03-31T16:50:32Z. The update package is 1.11 GB. This is a full OTA update that can be applied from any compatible base version. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b8d38d1224b2e5763d00423e17837a8b4309b615.zip.