If you have an iOS device with iOS 6 or later, you can Facetime without Wi-Fi using 3G or 4G data from your ISP. If you have an iOS device with iOS 5 or earlier, you can jailbreak your device and install 'My3G', an application that allows you to use Wi-Fi applications using your carrier's 3G network. If you have an iOS device and another FaceTime-enabled device, you can create a personal Hotspot to turn your iOS device into an Internet hotspot.
Steps
Method 1 of 3: On iOS 6 and later
Step 1. Tap on 'Settings', and then tap on 'FaceTime'
Step 2. Scroll down and set 'Use Mobile Data' to the 'on' position
This setting allows you to use 3G or 4G data from your ISP on your iOS device when Wi-Fi is not available.
Step #3. Navigate back to your home screen and open FaceTime
You can now make FaceTime calls without using a Wi-Fi connection.
Method 2 of 3: Enable Personal Hotspot on iOS 5 and earlier
Step 1. Tap 'Settings', then tap 'Mobile data' or 'Data'
Step 2. Tap on 'Personal Hotspot', and set this setting to 'on'
Step #3. Tap on 'Turn on Wi-Fi and Bluetooth'
Allows other Wi-Fi and Bluetooth devices to connect to your iOS device.
Step 4. Tap on 'Wi-Fi password' and enter the password for your Personal HotSpot
Step 5. Verify that your iOS device is visible under 'To connect to Wi-Fi'
This means that your HotSpot has been created.
Step 6. Connect to your personal Hotspot from another FaceTime-enabled device, such as an iPhone, iPad, or Mac OS X computer
You can now Facetime with your iOS device as a HotSpot.
Method 3 of 3: Jailbreak iOS 5 and earlier
Step 1. Navigate to redsn0w's website
Redsn0w is the software you will use to jailbreak your device so that you can use FaceTime without WiFi.
Step 2. Scroll down to the 'Jailbreak tools' section and select your computer's operating system from the drop-down menu
Step 3. Select 'redsn0w' from the software menu, and select the latest version from the Beta menu
Step 4. Save the file to your desktop, and double click on the file to extract the contents
Step 5. Follow the on-screen instructions to install redsn0w on your computer
Step 6. Navigate back to redsn0w's website http://www.redsn0w.us/2010/03/download-direct-links-jailbreak-guides.html and scroll down to the 'Get iOS' section
Step 7. Select your iOS device, model, and version from the drop-down menus
Step 8. Click on 'Download iOS' and select the option to save the file to your desktop
Step 9. Connect the iOS device to your computer with a USB cable
iTunes will launch automatically when your device is recognized.
Step 10. Select your device in iTunes, then hold down the 'Shift' (Windows) or 'Option' (Mac OS X) key, depending on your operating system
Step 11. Click "Restore [iOS Device]", and select the iOS-redsn0w file you downloaded and saved to your desktop
This will install jailbreak iOS on your device.
Step 12. Click back to your desktop and launch the redsn0w application
Step 13. Click "Custom IPSW" and select the same iOS redsn0w file you selected earlier in iTunes
Step 14. Click 'Next' and select 'Jailbreak'
Step 15. Check the box next to 'Install Cydia' and click 'Next'
Cydia is the program you need to download 'My3G', a software that allows you to use FaceTime without Wi-Fi.
Step 16. Follow the onscreen instructions to jailbreak your iOS device with redsn0w
When completed, Cydia will appear in the app tray.
Step 17. Launch Cydia and search for the 'My3G' application
My3G allows you to use Wi-Fi applications such as FaceTime using your carrier's 3G network. The app currently costs $3.99, but offers a free trial so you can try out the service.
Step 18. Tap 'My3G' and follow the on-screen instructions to purchase the app and sign up for the free trial
Step 19. When the installation is complete, launch 'My3G' and open FaceTime
You can now use FaceTime without using a Wi-Fi connection.