iOS 12.3 (build 16F5117h) is an official Apple over-the-air update for the iPhone 7 (GSM), released on 2019-03-27T17:06:31Z. The update package is 373.91 MB. This is a delta (partial) update that requires 12.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 7528029ffd433642b9842ecc8852c9b955be41e2.zip.