Iphone 4 keeps going dead when i was on the phone?

Sometimes wen i'm on the phone to people the call will go dead and when i click end call. It just keeps saying ending call. I then have to to turn the phone off to make it end call. What should i do to fix this

There's not much you can do. You can always try doing a hard reboot (hold down the Home button, and a prompt will appear), and if that doesn't work, head to your local Apple store. You can also call AppleCare and send it in for repair.

You can make reservations here: http://www.apple.com/.../geniusbar