Image: Pink phone © Fuse, Getty Images

Some debt collectors can be ruthless, calling all hours of the day and night and threatening arrest and violence if they don't get paid. Speaking in heavily accented English, they may use foul language, and they don't hesitate to lie about who they are, where they are calling from or what they will do to you if you don't pay up right away.

The thing is, these particular callers are not really debt collectors. They're extortionists and scammers, calling Americans from other countries as part of a long-running con to get money from consumers who at some point applied for online payday loans. One firm allegedly raked in $5 million before the Federal Trade Commission stepped in.

We've written numerous articles about how to spot an overseas payday-loan debt-collection scam. But what if you know it's a scam and you just want the calls to stop? A reader posed the following question on our blog recently:

"I have been receiving calls from someone who is saying I owe money to a First American Cash Advance. Well, first of all, I can't even get a payday loan -- I am in the military. Besides that, they [have] been calling my work and it's been difficult. The number appears on my caller id as out-of-area call (911). I'm not sure what that means. They say they work for the FBI and if I don't pay I could go to prison. I never even received anything in the mail about this, as well as never having a payday loan, so I know it's fake. I just want them to stop calling and harassing me. I can't even understand them and they're saying they will have me investigated. What should I do?"

Strategy No. 1: Do not engage. Do not get into a conversation with them in the first place. "Hang up on them," says Mark Fullbright, a senior fraud investigator with Identity Theft 911. "They are effective because people want to converse about the debt and prove they did not owe a payday loan debt. There is nothing to prove to these scammers. Do not provide anything to them."

Attorney William Howard with the Florida-based law firm of Morgan & Morgan warns that "Just like any other volume business they are calling thousands of people and they are looking for the vulnerable and the gullible." If it doesn't sound like they are going to get any money from you, they're more likely to move on to someone else.

Strategy No. 2: Ask for written verification. If you have defaulted on a payday loan and are worried this could be a real attempt to collect a debt, insist the collector put information about the debt in writing. This is your right under the federal Fair Debt Collection Practices Act, and legitimate debt collectors know they must comply, explains Howard. Don't settle for an email confirmation. And don't be intimidated if the caller threatens you, saying that there is no time for that because you'll be arrested today if you don't pay, for example. "You won't be arrested," says Howard.

Strategy No. 3: Turn the tables on them. If the caller tells you that the agency is taking you to court, "ask for the specific case number and court it is allegedly filed in," says Steve Rhode of "Call the court to confirm. You won't be able to because it's a scam." You'll know this is a scam before it gets to that point, anyway, because when you are sued you must be served with a written notice of the lawsuit.

If the caller claims to be with a law enforcement agency, ask for specifics: the caller's name and which agency he supposedly works for (for a police officer -- the specific city, county or state, for example). Just as you have the right to ask a police officer who pulls you over in an unmarked car for identification, you have the right to verify anyone who calls you claiming to be with law enforcement.

Let the caller know you will be calling that agency directly to confirm his identity before you talk further with him. Of course, you'll come up empty-handed, as neither the FBI nor police officers are debt collectors. Be sure to tell the caller that if his story doesn't check out, you are reporting the call to that same law enforcement agency. "Tell them you are going to call the cops on them," insists Howard.

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