iOS 9.2.1 (build 13D14) is an official Apple over-the-air update for the iPhone 4s, released on 2016-01-04T17:58:49Z. The update package is 23.18 MB. This is a delta (partial) update that requires 9.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: eb271478c0ed08d9d35df6fec46e8ea84430365a.zip.