iOS 9.9.11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2017-12-13T18:11:20Z. The update package is 1.25 GB. This is a delta (partial) update that requires 9.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 90304221774b67f149b8ae809e43bd1f228fb0cc.zip.