Keep your guard up on one of the most devastating scams to hit American tax payers.

Investigators with the federal Department of Justice, Homeland Security and IRS arrested and jailed more than 20 people across the country and in India accused of running that IRS phone scam.

That's the scam where you get called and threatened with jail unless you pay thousands of dollars. But you better keep your guard up on one of the most devastating scams to hit American tax payers.

The Department of Justice says it netted hundreds of millions of dollars from innocent people who got scared and paid up. And the IRS says other scam artists will fill the void.

In Greece, Marie Furino wrote down the voicemail left by one of the scam callers she got in June. Messenger Post's news partner, News10NBC asked her to read part of it.

"They said 'this is the IRS calling,'" Furino said. "'The IRS is filing a lawsuit against you for tax fraud.'"

The message said Furino would be arrested if she didn't pay. It was the second such call she received in a year.

"I think it's terrible especially for the elderly people who fall for it and don't have the money," she said.

Millions of people have received this call, including News10NBC's Deanna Dewberry. Deanna recorded the threat.

Scam caller: "The police department and an IRS investigator will be coming to your door steps or your work place within in 30 minutes and they can keep you under their custody for the next two months."

News10NBC's Deanna Dewberry: "They can arrest me right now?"

Scam caller: "That's correct Miss."

Now, more than 20 people behind that scam are arrested or in prison. News10NBC reached out to the IRS Tuesday afternoon whose agents were part of the investigation.

Christopher Miller, IRS spokesperson: "Any time you're able to take these criminals off the street and get them away from innocent taxpayers and away from stealing their money, it's a step in the right direction."

But Christopher Miller of the IRS says the scam is so profitable, he expects other crooks to pick it up.

News10NBC Chief Investigative Reporter Berkeley Brean: "If people continue to get these calls, what do they do?"

Miller: "If you happen to get one of these IRS impersonation phone scam calls, we want you to hang up."

Marie Furino dialed the number the scammers told her to call.

Here's what the message says now:

"The number you have dialed is being investigated for unlawful use or other fraudulent activity."

Like the IRS, Furino isn't convinced the arrests mean this problem is over.

"It may stop these guys, but someone else will take it up," she said.

If you receive a call from someone saying he or she is from the IRS and threatens you with jail or deportation if you don't pay money, hang up and contact the U.S. Treasury Department Inspector General for Tax Administration.

You can report a scam by clicking here.