iOS 9.2.1 (build 13D15) is an official Apple over-the-air update for the iPhone 6s, released on 2016-01-19T18:20:44Z. The update package is 269.91 MB. This is a delta (partial) update that requires 9.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 098697af1978ed0c26e17b8a6540fe2c08de99c5.zip.