The fake operators disguise the number to look like the National Do Not Call List, a government agency that removes people's phone numbers from telemarketers' lists.
"It looks like they're phishing for information… so they're giving this line where it says. 'Your number is about to expire, and we need to update it with your current information," said Evan Kelly, a spokesman for the Better Business Bureau. "And that's where they're getting your personal information, and that's where it gets really really fishy."
In fact, numbers that are already on the National Do Not call List are permanent and can't be removed without a person's request, he noted.
Also, government agencies never solicit personal information over the phone, and that any scam call should be reported to the Canadian Fraud Centre immediately, the BBB added.
"Scams usually involve fake businesses or fake charities," Kelly said.
"However more and more these days we are hearing about government agencies being impersonated. It adds a new element of believability for the unsuspecting victim on the other end of the phone. It creates a greater sense of urgency which the scammer is trying to instill."