I called the owner and asked how you got my phone number. What should you say?

That depends on your identity. If you are the owner, call the owner and the owner will ask you why you have a phone. Of course, you can just say it. There is a telephone number of every owner in the property, because in order to serve the property conveniently, all owners' telephones will be registered in case you have anything at home to contact the owner. But if you are just an outsider, who will have such questions? After all, the telephone is a very private thing, generally only friends and relatives, and everyone is afraid that their telephone will be leaked and used by others.