iOS 9.1 (build 13B143) is an official Apple over-the-air update for the iPhone 6, released on 2015-10-21T17:16:05Z. The update package is 1.12 GB. This is a delta (partial) update that requires 8.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: e824627f42f2a7160f5c566b806e752a3353eaa4.zip.