I agree with Brian: I don't think it's possible to detect an autodialer at the hardware level. I think detection would be more in the usage patterns. If someone is "wardialing" numbers continuously, it's probably an autodialer rather than a person sitting at the phone dialing numbers manually. But your security autodialer should make calls seldomly and shouldn't trigger such detection. Another method would be detecting the dial pattern. If there is always the same gap between going off-hook and dialing the first number and each remaining number is dialed with the same tone duration and interval, it would be an autodialer rather than a human, though this detection method could yield false positives when a human uses a phone with "speed dial" keys.
Though these methods could be feasible, I don't know if any phone companies are using either of them.