iOS 6.1.3 (build 10B329) is an official Apple over-the-air update for the iPhone 4 (CDMA). The update package is 879.92 MB. This is a delta (partial) update that requires null already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 56070a7122a5450ef707388283edef23c41ec035.zip.