After installing iTunes, plug in your iPhone and let it complete any patch updates or system backups.
Then, find your iPhone under "Devices" in the left-hand explorer bar, right-click it, and select "Transfer Purchases."
See http://theappleblog.com/2008/07/22/transfer-applications-from-iphone-to-itunes/ for screenshots.
log into your itunes account and restore purchases.
There are many other ways of backing up messages and emails on iphone imactools.com/iphonebackupviewer/
If your iPhone has an aluminium backing, with a black cover down the bottom then it is a 2G. To differentiate between an iPhone 3G and 3GS, look if you have an app called 'Compass', if you do then you have an iPhone 3GS. The iPhone 4 is easy to identify because it has a flat backing and is more rectangular in shape.
Actually, It doesnt. 'Cause its the purpose of backing up the data. After the update, Your iphone will restore then it will put back your old data.
Backing information up on an iPhone is simple and easy. All you have to do is sign into Google Plus and save everything to your account.
Only if you've saved your SHSH. If you don't know what that is then no sorry.
It is very difficult to answer this, but the main differences between the 5 phones Apple offers is Camera, backing, Siri, and several tweaks and fixes. So far the iPhone 4s overrules al of them.
An IPhone 4s without a contract is $600.00 or $650.00
Not without a Qi compatible external iPhone shell.
An iPhone without a contract is a fancy coaster or paperweight worth nothing.
Not possible.
How much does an iphone 3G cost without network in the UK?
Download installous on iPhone (In the IPhone Store)