iOS 9.1 (build 13B5136) is an official Apple over-the-air update for the iPhone 4s, released on 2015-10-06T17:54:05Z. The update package is 1.09 GB. This is a delta (partial) update that requires null already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 835e2fe139ca1e0f8697e02a73a35082076fe8b2.zip.