iOS 9.1 (build 13B5130b) is an official Apple over-the-air update for the iPhone 6s, released on 2015-09-30T17:58:12Z. The update package is 216.5 MB. This is a delta (partial) update that requires 9.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: ff52e7b8d6fb55506d3fd5f334ec939ae0acb1b8.zip.