iOS 9.1 (build 13B139) is an official Apple over-the-air update for the iPhone 6s, released on 2015-10-12T16:56:58Z. The update package is 1.43 GB. 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: 225212fa2091eddbae0b520370cece48386194dc.zip.