iOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone 7 (Global), released on 2017-12-13T18:14:35Z. The update package is 391.68 MB. This is a delta (partial) update that requires 11.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 48181b0f63853e7ac0b1c5f37cab0415a6fe3c83.zip.