Unfortunately, there are countless cell phone scams out there: sometimes they're just spam, and other times – and they're increasingly common – a “Hey Dad, Hi Mom” ​​scam. However, there are those that simply consist of a missed call, of course from an unknown number.

A missed call, i.e. a call you don't answer or interact with someone, seems unlikely to pose a risk to you and your money. However, it “hides” one of the most effective scams in the world, and its great efficiency is due precisely to the simplicity of the scam.

Now look: When you receive a notification on your cell phone, the natural thing to do is to open it and see who it is or what it was. We do the same thing during a call, with one difference: we often try to verify by redialing the missing number.

What does the scam consist of? To hide the call, cybercriminals call your cell phone, but hang up after two or three rings so you don't have time to answer. Call backs are exactly what cybercriminals want, as the numbers refer to phones located out of the country, meaning a call back could leave you paying additional fees.

Cybercriminals get a percentage of the fee charged to the victim and may get an additional amount if the victim stays on the phone for a period of time.

The Spanish Civil Guard warns of the problem, pointing to a series of phone numbers that should be avoided to avoid falling victim to this scam. If you see a missed call from a number with any of these prefixes, it's best to ignore them: 355 (Albania), 225 (Ivory Coast), 233 (Ghana), and 234 (Nigeria).

These are the most common numbers, but they are not the only ones. As we know, cybercriminals update and modify their scams to anticipate users' prevention measures.