When people call the wrong number, they make it out to be your fault because they picked up the phone with expectations, and when you answered, you ruined their plans. You're not what they wanted.
When I was sixteen, my mother and I moved into a little house, far, far away. She was hiding from my father then, and she asked the telephone company for an unlisted number. "Certainly," said the communications technician. "I have the perfect number for you! It became available yesterday. 555-6591."
By the end of the week, we started getting some fairly off-kilter phone calls. Sometimes there was heavy breathing. Sometimes there were several people at once. They called at midnight. They called during breakfast. All of them, looking for Gail. Most of them became pretty angry if I told them Gail wasn't around. "It isn't fair," they whinged, "since Gail told me I could always reach her on this number. Did you send her away? Did you make her leave?"
"Is there anyone else there?"
"Why, yes," I said, "there's me."
"What's your name?" he asked. "Do you want to talk?"
"No," I said warily.
"Well, what use is your phone number then?" he snarled. The phone clicked softly in my ear as he ended the call.
A month later (by which time the sound of the phone was giving me a nervous twitch in my eye), my mother handed me the receiver. "It's for you," she said quizzically.
I lifted the phone to my ear. "Hello?"
"Hi," said a soft voice with a gentle drawl. "My name is Lisa. I'm Gail's sister. I understand you've been getting a lot of phone calls for Gail?"
"As it happens, yes. I didn't write them down; there were rather a lot of them..."
"That's okay," she said smoothly.
"Er, if you don't mind my asking, what does Gail do for a living?"
"Oh, Gail runs a fantasy phone sex hotline. Our number - well, your number now - is published in magazines all around the country."
"By the way," she mused, "you sound very young: sixteen, I think?"
"Going on seventeen," I replied.
"Gail runs a special service," she said. "She picks up the phone, pretending to be some housewife, then changes her tone and pretends to be a seventeen-year-old schoolgirl. The boys probably thought you were toying with them. You have a nice voice; no wonder they kept calling back."
There was a pause. "Do you work, after school...?"
"I work at a bookstore."
"You could work from home..." her voice trailed off as I hung up the phone.
In summary, sometimes people who get the wrong number make it out to be your fault because they're disappointed that you're not a middle-aged phone sex operator pretending to be a seventeen-year-old schoolgirl.