Unlocking the Tethering your iPhone 3G and 3GS:
Step 1: Once you are done with the jailbreak and unlock, start Safari web browser on your iPhone and navigate to:
Step 2: Scroll down to where it says “Mobileconfigs – download >”
Choose your country, and then your service provider.
Step 3: Safari will now prompt you to install an unsigned Tethering .IPCC file on your iPhone. Allow the file to install by touching on install button.
Step 4: Now reboot your iPhone by first holding down the “Home” button, followed by “Power” button simultaneously until you see Apple logo on the screen.
Step 5: Once your phone has been restarted, simply navigate to
on your iPhone and turn on the toggle for Internet Tethering.
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