It’s a known fact that official iOS devices sold in the UAE don’t have FaceTime installed and UAE is not available in the list of countries when signing up for iMessages. However, with the upgrade to iOS 6, some people are facing issues trying to activate FaceTime or iMessages even if they have an imported device that worked well with the above two services on iOS 5.
What is happening is that in IOS 6, Apple is also checking the address defined in your Apple ID associated with your account. So while creating your Apple ID, if you chose UAE as your location, you will not be able to validate your email/password in iMessages or FaceTime under iOS 6.
There is a simple way of getting this to work though. On your newly iOS 6 updated iPhone or iPad, go to the iTunes App and scroll all the way down to the bottom where it says Apple ID : (your account). Tap on your account and select View Apple ID. Here you will see an option to change your Country/Region and chances are that UAE is currently selected for your account. Change this location to another country such as UK, US or wherever else you fancy and accept the new agreement.

You might need to enter a valid address for the country you chose as your new location so make sure you have one handy. Once this is done, go back to iMessages and/or FaceTime and sign in with your Apple ID. You should now be able to sign into both of these services. Once you are signed in, you can go back to iTunes and change the location of your account back to the UAE