iOS 8.3 (build 12F5047f) is an official Apple over-the-air update for the iPhone 4s, released on 2015-03-12T16:56:09Z. The update package is 54.06 MB. This is a delta (partial) update that requires 8.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a36ef08528011ee42175314b6c2ad6f1ecf61692.zip.