Many of us forced to upgrade firmware because new apps are not supported on current firmware version. Updating firmware also increases the chance of locking iPhone.All this has been taken care through Firmware 3.1.3 app. This app lets you to change the firmware version from 3.1.2 to 3.1.3. Literally the firmware version is not updated to 3.1.3. Instead it justs tricks your device into thinking you are updated to OS 3.1.3.
SO Apps of appstore and iTunes will think that there firmware version is 3.1.3. Even any app written for 3.1.3 should run on 3.1.2. Once this is installed even iTunes will not ask you to update your iPhone firmware version, which is quite helpful if you are a non technical user avoiding you to prevent accidental updates.
Firmware 3.1.3 is available on cydia under BigBoss repo for free.
URL: HTTP://apt.bigboss.us.com/repofiles/cydia/
