iPhone 4s can't make or recieve calls or messages
I have just purchased an iPhone 4s on T-Mobile. My 3G works fine for web browsing but I can't make or receive calls or messages. I've tried resetting the phone and even a reinstall of the latest OS update but to no avail. I've seen that people have similar issues and I've tried all the suggested 'fixes' that I can find too but again of no use. I assume that my phone must be faulty and not a network issue as 3G is working for web but happy to try any other suggestions people may have in the meantime.
iPhone 4S, iOS 5.0.1