How do I turn off auto answer?

Here's how:

1. Launch the Settings app from the Home screen of your iPhone.
2. Tap on General.
3. Scroll down towards the bottom and tap on Accessibility.
4. Now tap on Incoming Calls under the Physical & Motor section.
5. Here you have the option to toggle between Default, Headset, and Speaker.

Are you referring to not having calls go to voice mail?