How does the next paragraph end?

How to introduce a new dog to visitors
Ask your visitors to call you instead of knocking on the door or ringing the bell.
The sound of an arriving guest might upset the new dog. Therefore, you should ask all potential visitors to call you before they arrive at the house.
Alternately, or in addition, you could put an " out-of-order " sign over your doorbell to prevent its use altogether. Your dog might also be afraid of or agitated by a knock at the door.