iOS 8.1.3 (build 12B466) is an official Apple over-the-air update for the iPhone 4s, released on 2015-01-27T17:55:05Z. The update package is 148.75 MB. This is a delta (partial) update that requires 8.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: ec3c0e1f2e6e848d4017da3dccf0bdc7bf992b0a.zip.