This number has called me a few times too. I didn't answer the first time, but the second time I did answer. I said Hello a few times but there was no reply on the other end. After about thirty seconds, I just ended the call.
You are making the same assumption everyone else who has been scammed by this offer. NO THE BOTTLE IS NOT FREE - you have to pay for it after the trial period. You get it for shipping and handling, but they do charge you for it once the trial period has ended. Says so in the terms and conditions..