Installing ios7 :
Installing the ios7 beta on the iPhone 5 and iPhone 4S is pretty easy with direction. Make sure you receive confirmation that the UDID is registered otherwise this will fail. This could take some time, especially if you choose to restore from backup, so budget accordingly.
1. Register the device UDID with IMZDL
2. Make sure you are on the latest version of iTunes.
3. Connect the iPhone to the computer and perform a backup with iTunes.
4. Download the iOS 7 Beta for your iPhone model. The files will show up on IMZDL today, but could take time.
6. Open iTunes and upgrade to the iOS 7 Beta by choosing Restore.
- Be sure to hold alt/option on Mac when you click Restore.
- On Windows, hold Shift when you click Restore.
7. Find the .ipsw file you downloaded and select it.
8. Complete the installation and then restore from backup if you desire.
This will install the iOS 7 beta on the iPhone 5, iPhone 4S or iPhone 4. An iOS 7 beta for iPad and iPAd mini will come later.