can I auto redial on my iphone 4s

Could you possibly give a few more details about what you're trying to accomplish? Do you mean you want to phone to keep dialing somone until they answer? I don't know as that's possible on any phone.

the only way that I know is to hit the Call button and the iPhone will present you with the last number you dialed. Tap the Call button a second time and the iPhone will redial that number.