When your cellphone rings, there’s a good chance a scammer is calling. And even if you’re a savvy person, it’s easy to be fooled.

A recent survey of 1,000 mobile phone users found that millennials are particularly susceptible to phone scams. Similarly, the Federal Trade Commission’s tally of 2017 consumer complaints found that a larger share of Americans in their 20s reported losing money to fraud last year, compared to older individuals. And fraud, unfortunately, is big business. Americans lost almost $905 million to fraudsters last year, an increase of $63 million over the previous year.

Among the most popular scams: phony debt collections (23 percent of all reports), identity theft (14 percent) and impostor scams (13 percent), in which the caller poses as a trusted person such as a government worker, a tech support agent or a family member in an emergency.

The types of scams that tend to incur the biggest dollar losses: travel, vacation and timeshare-plan schemes, mortgage foreclosure relief, and business and job opportunity scams.

Although the popular image of a fraud victim is someone who’s older, those ages 25 to 34 were the most likely to lose money to some type of fraud, according to a 2016 study from the Better Business Bureau. Why are young people vulnerable? Some financial experts blame “optimism bias.” One study showed that millennials were more confident than other generations when determining whether an email, text or phone call was a scam. If you assume that fraud won’t happen to you, you may take more risks.

Younger people are also more accustomed to making online purchases and sharing personal information. That may explain why millennials were six times more likely than Baby Boomers to disclose personal information over the phone if the caller could verify the last four digits of their Social Security number. Phone scammers are diabolically crafty; they use tidbits of personal information – usually stolen data - to coax victims into giving up more information.

How can you stay safe? If someone calls you offering a deal that’s too good to be true, chances are it’s a scam. Never give out personal information over the phone, unless you’ve placed the call yourself to a trusted business or organization. (If you do receive a call that might be legit, find the company’s 800 number from a solid source, such as a credit card statement; call and ask if there’s an issue that truly needs your attention.)

Finally, remember that scammers come up with new ways of tricking people every day. Even fraud experts fall for scams from time to time. No matter how smart you are, be wary.