iOS 9.3.1 (build 13E6238) is an official Apple over-the-air update for the iPhone 6s, released on 2016-03-31T16:50:36Z. The update package is 1.46 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: 15463de3049f882a631c7b7b8bd72cc9fe6736af.zip.