i was able to update my iPhone 4S and iPad via the option on the settings menu however i iPhone 4 which i use as my music player doesn't have that option, my computer with itunes doesn't connect to the internet so i can't download it via itunes
i am wondering if there is an offline installer i can download that itune can detect to use, that way i can download it on a separate computer then transfer it to my main computer
Best Answer
There exists direct download links for the restore images that you can download from one computer and use for the restore on your own computer, however you will still need an internet connection for the final part of the installation (iTunes needs to verify with Apple servers).
Once you have the .ipsw file on your computer, hold down ⌘ Command (or control if on a PC) while clicking 'Update' in iTunes, and select the .ipsw file for your iPhone.