So then they won't be able to ring the door so they will knock and the dog will then flip out about the knocking??? Not sure what the goal here is.
Dogs instinctively are alarms. In the wild when one of them sees something or hear something they start yapping and the rest of the pack starts yapping.
I generally love it when our dog starts barking when someone is at the door because I know that in the hours we are gone and the dog is the only one in the house, that when the bad guys come and start shaking the door handle or ringing the doorbell to see if it's an easy target to hit, the dog explodes, the bad guys hear it and run off.
You might want to re-evaluate this. Your getting a huge benefit from the doorbell and dog combo that you apparently don't realize you have. Your house might have been hit already without the dog doing his job.