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 721 MB. This is a delta (partial) update that requires 7.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 3f72437008ebac84fe45c5cf2198e151bcf129f9.zip.