Am I the only one unable to hear busy signal on the iPhone 5?

With my previous iPhones (3G and 4), if I called someone and he refused my call after a short while, I heard the busy signal. Now with the iPhone 5 I don't here anything at all. What I get is the screen telling me the person is busy with the choice to recall or not.

Example:

Call from old iPhones -> tuuuuut . . . . . tuuuuut . . . tut tut tut

Call from iPhone 5 -> tuuuuut . . . . . tuuuuut . . . silence

Am I the only one? Is this expected behavior? I tried resetting carrier settings and even restoring the phone, but nothing changed. I think this is this an iPhone 5 problem, because an iPhone 4S with iOS 6 acts like normal (same carrier).