Tethering on iPhone allows sharing internet connection with computer via USB cable or Bluetooth in which iPhone act as a wireless modem for computer. With Internet tethering on iPhone, you does not need a Wi-Fi hotspot to access internet from your computer. You can easily share the internet connection on your iPhone with your Mac notebook or PC laptop and connect to the Internet anywhere. When your iPhone is tethered, you can still send and receive data and make phone calls.
Steps to Enable Tethering on iPhone 3G/3GS with OS 3.1.2 Firmware
Step 2- Once your iPhone is jailbreaked navigate to Cydia and Search for ‘MyWi’ app for installation.
Step 3- Launch the MyWi (Rock app) and navigate to – Manage > Rock ID > Create New RockID
Step 4- You might need to update to new version of MyWi app. Once updated you will be prompted for ‘Soft Restart Required’. Click ‘Ok’ to continue.
Step 5- Open MyWi and turn the USB and Bluetooth Tethering option ON.
Step 6- Reboot your iPhone device.
Step 7- Navigate to Settings > General > Network > Internet Tethering and make the Tethering ON
Your iPhone 2G/3G/3GS is now Tethered on iPhone OS 3.1.2.