What should I do if an unknown cat is yelling at the door? If a cat you don't know is yelling at the door, you can try ordering food for it, or try taking it home to see if it has a owner. If it doesn't have a owner, you can consider adopting it. You can also let it go so that it doesn't cause trouble.
The cat you don't know is mostly lost when you call at the door. You can post a group photo from the owner to find the owner. The cat may be hungry and seek help. You can give the cat some water and food to eat.
If there is a female cat at home, it may also attract male cats in estrus to gather at the doorstep of the house. There is also a superstitious saying that someone in the family is going to have a baby, or a guest from afar is coming to the house.