iOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone 7 Plus (GSM), released on 2017-12-13T18:15:05Z. The update package is 1.23 GB. This is a delta (partial) update that requires 10.3.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: de4c347b352981f417d587d0eeef1c0d35d5feec.zip.