What happens when I reset the call statistics on an iPhone?
After a quick test, everything but "Call Time: Lifetime" and the statistics under "Time since last full charge" was reset.

It only makes sense that the field "Call Time: Lifetime" doesn't get reset since it shows the the total physical time the phone was being used to call.  If it was restored and set up as a new phone I believe that the setting will then be reset since it will be technically a new life for the phone.  Unless AT&amp;T/Verizon keeps track of that data through your number.  Then you would change your number to reset that field.  Though I wouldn't be trying that anytime soon.