iOS 9.1 (build 13B5137) is an official Apple over-the-air update for the iPhone 4s, released on 2015-10-12T16:57:00Z. The update package is 1.09 GB. This is a full OTA update that can be applied from any compatible base version. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 93ba05244744f15117feb116d2b6343836e9e6e7.zip.