How To Update and Install iOS 7 GM on iPhone, iPad and iPod Without UDID
If you are currently using iOS 6.1.2 or lower, you should upgrade your iPhone, iPad and your ipod to iOS 6.1.3 or 6.1.4, before installing iOS 7 GM. This aims to avoid errors during the process of upgrade.
Update your iTunes to the latest version at this time (11.0.5). Remember to install iOS 7 on iPhone, iPad and iPod will remove the jailbreak. iTunes does not support the current version of iOS 7, so you can not move a or insert files such as music, videos, etc. using iTunes. Until iTunes 11.1 version released to the public.
If you already know and understand the lack if installing iOS 7, and impatient waiting iOS 7 final version which will be released on 18 September 2013. please follow the steps below.
Also make sure that your devices support with iOS 7, for see the support iDevice with iOS 7 you can see via this link
How To Update and Install iOS 7 GM on iPhone, iPad and iPod Without UDID
Step 1: Make sure you are using iOS on iPhone, iPad and iPod touch is iOS 6.1.3 or iOS 6.1.4.
Step 2: Download iOS 7 GM IPSW files via this link.
Step 3: If the IPSW file that you downloaded with the extension DMG, use applications dmg extrator for windows to obtain ipsw file
Step 4: Connect your iPhone, iPad or iPod to your PC or laptop and open iTunes.
Step 5: For Windows press the Shift key and click Update, For Mac OS X Click Option keys and click Update Not
Step 6 : Click on Open, then please be patient until the update process is complete, about 10 minutes.
After you successfully install iOS 7 GM, continue with the activation process. your device should connect to wifi.
