If You are not able to unlock your iPhone 4S fro AT&T, You can try unlocking it from any trusted vendor online. For example, You can get remote unlocking for your iPhone 4S from,
www.wickedunlock.com/apple-iphone-4s/rs11wp9/ This method of unlocking is safe, simple and affordable. The unlocking process is very simple here.
Here are the steps for unlocking an iPhone 4S,
1. Wait for us to send you an email saying your phone has been activated or remotely unlocked.
2. Install the latest version of iTunes.
3. Make sure your Apple iPhone 4S phone software is updated to the latest version using the iTunes software.
4. Connect your Apple iPhone 4S to iTunes with a
NOT ACCEPTED SIM card.
5. Wait until iTunes detects your Apple iPhone 4S.
6. Disconnect your Apple iPhone 4S and reconnect it after 10 seconds.
7. Your Apple iPhone 4S is now unlocked.