A London, Ont., man took the law into his own hands after he says he kept calling a group of telephone scammers until they begged him to stop.

Kevin Underhill got a call from phone scammers who were posing as the Canada Revenue Agency on Tuesday morning.

"It was actually very terrible voicemail," he said. "It was very robotic. It stated that it was the Canada Revenue calling and there was a pressing matter of serious consequence and they were starting criminal activity."

Underhill's gut told him it was a scam and it didn't take long to confirm his suspicions.

'I called them back the first chance I had'

Kevin Underhill turned the tables on phone scammers, pestering them with repeated calls until they begged him to leave them alone. (Submitted)

"I called them back the first chance I had," Underhill said, noting that unlike the real Canada Revenue Agency, he didn't have to go through multiple phone menus in order to speak to a human being.

If I keep calling back and waste their time, then it's one less person that they're able to reach. - Kevin Underhill

"It took two rings and an agent was on the phone," he said. "This was immediate."

Once Underhill knew he could get through easily, he said he just kept calling on his lunch breaks, over and over again.

"I called many times to tie up their lines," he said.

How Underhill got his revenge

Underhill said he had a few favourite pranks he pulled on the fraudsters.

"When they asked my name, I said 'I'll spell it: Y-O-U, middle initial: R, last name spelled: A-S-C-A-M," and once he typed that into the computer, I said 'Read that back to me, make sure you got that right.'

"Then he said 'Wait a minute, that's not your name' and he clicked in and hung up," Underhill said. "I called them immediately right back."

Underhill said he pretended to be confused and that he had been disconnected and he was trying to find out what happened.

'Stop pranking us'

"One guy fell for it," he said. "I gave him a different name and he went through the whole thing and said 'You have committed income tax fraud and you also have some kind of disability fraud as well and we're starting litigation on you on criminal charges.'"

"I'm like 'Are you kidding me?' I just got out of prison, I've been serving 10 years for fraud and my lawyer told me this was all going to go away,'" he said. "They just hung up on me."

After that, Underhill kept calling, over and over and over, until someone finally answered.

"Another guy took the phone away from him and said 'Stop calling us.' I said 'Who's this?' He said 'It's the manager of the CRA.' I'm like, 'Oh, why do you guys keep hanging up?' He goes, 'Leave us alone. Stop pranking us,'" Underhill said.

'Most people don't go as far as me'

Kevin Underhill took it upon himself to repeatedly prank call a group of telephone scammers in order to keep them from calling their marks. (Shutterstock/Gajus)

While most people ignore it when they get a call from someone posing as an agent from Revenue Canada, Underhill said he just couldn't resist the urge to get the best of people who were trying to take advantage of others.

"Most people don't go as far as me," he said. "But I also know that if I keep calling back and waste their time, then it's one less person that they're able to reach."

"Senior citizens, that's where my worry is," Underhill said. "Certainly there are grandparents that don't use the Internet, don't follow social media and don't know about this."

Underhill said once he felt the scammers had had enough, he called police to report their activities.

"She was a really nice officer," he said. "She told me to call the media. She said 'I'd start with CBC.'"

Underhill said while the officer was helpful and gave him several numbers, including the RCMP and the Canadian Anti-Fraud Centre, police said there's really nothing they can do to stop the scammers.

In 2015, Canadians reported losing $61 million to scams, a figure the Better Business Bureau of Canada believes represents only five per cent of the $1.2 billion the BBB estimates Canadians actually lost to scammers that year.

CBC News calls the scammers

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CBC News called the scammers under a phone number with a 613 area code provided by Underhill in order to ask why they did what they did.

"I think I'm a fool and you're a fool," an unidentified man on the other end of the line said.

When asked for clarification, the man repeated his answer.

"Man, I'm giving you a straight answer. You're a fool or I'm a fool who's giving you an answer to your stupid question," he said, before hanging up.