evidence: It can be tricky because many real banks have a similar system. And, Balasubramaniyan says, fear does kick in. He recalls a big scam in 2014 in which criminals pretended to be the IRS calling to collect back taxes. (The agency says the scam is still going on.) If you wanted to call back or have time to talk to your spouse before paying over the phone, the fraudster wouldn't let you go. [...] Company researchers estimate 1 in every 2,200 calls is a fraud attempt. And they've observed an interesting detail about the fraudulent 1-877 numbers. If you call back from your phone — which the criminals dialed — you get the prompt to enter personal data. If you call back from somewhere else, you get "this number has been deactivated." So a regulator or police officer that's trying to crack down will think, incorrectly, it's out of commission. Once the criminal ring scrapes enough information on you, it has humans call your financial institution. Banks and credit card companies hire Pindrop to help them detect fraud.