Yesterday, iPhone hack GeoHot released Blacksn0w, an unlock for the iPhone 3G and 3GS.
Note: You can also follow Universal iPhone Internet Tethering
Let’s start the 3.1.2 specific Tether
Step 1. Jailbreak, Unlock iPhone 3G, 3GS using blackra1n. Open the Blackra1n app .(This assumes that you “sn0w”, then hit the Install button. )
Note:If you have problems with WiFi, GPS, or YouTube after unlocking with Blacksn0w. If you have any such issues, go to Settings > General > Reset> and hit “Reset Network Settings”. Once that’s complete, do a hard power cycle by holding the sleep/home button for a few seconds and then sliding the on-screen power toggle.
Step 2. Open Safari. Navigate to: http://m.peacefulinsanity.com/Tether.mobileconfig
Step 4. Close Safari. Hold the sleep and home button until your iPhone resets. This reboot may take a bit longer than normal.
When your iPhone resets, go into Settings > General > Network > Internet Tethering. If you can successfully switch the “Internet Tethering” slider to “On”:
Congratulations! Everything seems to have worked as expected.
Enjoy your jailbroken, tetherable iPhone 3G/3GS on OS 3.1/3.1.2!
If you need any assistance, feel free to ask below, we will be happy to help.