Starting in 2024, Natasha Lavoie began getting calls on her cellphone from people who said they had found a missing cat named Torbo.

But Ms. Lavoie’s cat is named Mauser, and each time a call came, her black cat was where he was supposed to be, in her home in British Columbia, Canada.

This went on for a year.

Finally, about two weeks ago, she handed the phone to her partner, Jonathan McCurrach, who demanded to know why one man was calling so many times late at night.

The man admitted he was calling as a joke: His son had bought a shirt online that advertised a cash reward for a missing cat and listed a telephone number to call.

That telephone number was Ms. Lavoie’s.

Her cellphone would ring in spurts. For days in a row, she’d get multiple calls, even in the middle of the night. Then two weeks would pass without calls.

“At first I was thinking, like, who did I anger?” she said. “Who posted my number somewhere?”

She contacted the American company that sold the shirts, Wisdumb, to find out why and how it chose her phone number.

The company told her that its promotional run of the shirts had ended but then cut off any communication with no further explanation, Ms. Lavoie said.

The company took the shirt off its website, but it still has posts about it on TikTok. Text on one video says, “I made this thermal (shirt) to help find my cat.”

Ms. Lavoie said that she did not want to change her phone number because it’s been hers for nearly 20 years, and that the damage was done. Her phone number is out there, on shirts and on social media.

“I’m basically being harassed over a cat,” she said. “I’m getting calls all throughout the day, all throughout the night.”

Wisdumb did not respond to a request for comment. CBC reported earlier about Ms. Lavoie’s deluge of calls.

The company sells shirts with two different photos of a white kitten, with “missing cat” above the photos. Sometimes the cat’s name is Torbo. Other times it is Kawahira.

Neither cat looks like Mauser, described by Mr. McCurrach as a “short-haired fat black cat.”

Ms. Lavoie isn’t the first person to unexpectedly be on the receiving end of a personal phone number that was widely promoted.

After Tommy Tutone released the song “867-5309/Jenny” in 1981, listeners called the number with various area codes. Years later, one man tried to sell his version of the phone number.

Ms. Lavoie said learning why she was getting the calls was comforting. Before that, it was concerning because it was not clear who was calling or why.

Mr. McCurrach said a few callers had been rude or insistent.

“Some of these people are like: ‘I’ve got your cat. I want my money,’” he said. “And it’s like, who the hell are you? Go away. What are you doing? Leave me alone.”

Now that the couple knows why the calls are coming, Mr. McCurrach sometimes jokes back that he has the caller’s cat.

He also has some demands of his own.

“I don’t want a cat, I want a goat!” he tells callers. “Do you have any parakeets?”