The Cat Says Woof
Sending photographs of lovely dogs is one technique to let someone know they have the wrong number. It’s not a very common one, but it’s one that tells the person on the other line to stop bothering you without using those exact words. Of course, that’s only assuming that the other person knows what a dog is.
How could someone not know what a dog is, you ask? Well, you’d be surprised. This person, who had mistaken the OP for someone else (or maybe it was the other way around) couldn’t tell whether the images being spammed onto their phone was a cat or a dog.