iOS 12.1.3 (build 16D5039a) is an official Apple over-the-air update for the iPhone 5s (Global), released on 2019-01-10T18:09:07Z. The update package is 34.01 MB. This is a delta (partial) update that requires 12.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: cf066407827dd23d63dd1687c46930c3806ed3f7.zip.