Summary: According to a study by the American telecommunications company Verizon in 2024, phone numbers were found in 39 percent of all data breaches. Recently, a data breach at the American company Charter Communications resulted in the theft of 42 million records including customer phone numbers. So how can hackers hack our phone numbers, and how can we protect ourselves adequately?

Mobile phone numbers are used in a number of daily activities, such as verifying access to accounts, using ride-sharing apps, obtaining event tickets, boarding passes, and of course communicating with friends, family, and colleagues. This means that hacking our phone would have severe negative consequences on our personal lives.

Therefore, our mobile phone numbers are a gateway to fraud and cyber theft, and are used as a primary means of identity verification and account recovery for financial and social media accounts. Hackers today can obtain consumers' phone numbers from many sources, public and private, in addition to data breaches and data brokers.

According to a study by the American telecommunications company Verizon in 2024, phone numbers were found in 39 percent of all data breaches. Recently, a data breach at the American company Charter Communications resulted in the theft of 42 million records including customer phone numbers. So how can hackers hack our phone numbers, and how can we protect ourselves adequately?

Spam messages and false notifications

Some messages sent to our phones contain links to fraudulent websites, while others may aim to get a reply indicating that our number is in use. For example, some people in the United States and Europe receive text messages with the subject "Did you authorize a $200 deduction? Reply yes or no." When they reply "no," a person claiming to be from the anti-fraud department calls them, thanks them for the alert, and says they will secure their account and need a verification code. This code is actually an attempt by the attacker to change the password.

Hackers today can obtain consumers' phone numbers from many sources (AFP)

Perhaps no less dangerous are calls or text messages from entities claiming to be governmental, usually claiming to be highway authorities, the tax authority, the Social Security Administration, or local courts.

SIM swapping

SIM swapping, a small chip inserted into your phone to store your digital identity and encryption key, is the most dangerous and harmful type of phone number hacking. The attacker takes over the victim's phone number and pairs it with personal information that allows them to contact the mobile service provider. If they gather enough information illegally to convince a customer service representative of the telecom company that they are the legitimate owner of the phone number, the victim's account is transferred to a replacement SIM card.

For example, the attacker may fabricate a story about losing the phone or SIM card, and needing to transfer his number to a new one. Once the attacker controls the victim's number, he can intercept passwords and access your bank account and other sensitive services.

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Preventing SIM swapping requires a combination of vigilance and technology. The US Federal Communications Commission recommends using eSIM cards because of the greater security advantages they offer. To determine if you have a SIM or eSIM on an iPhone, go to Settings, then General, then About, then scroll down to see the type. On an Android phone, check the SIM card slot on the side of the phone, or go to Settings, then Network & Internet to check the SIM configuration type.

Number porting fraud

Similar to SIM swapping, number porting fraud involves fraudsters using the victim's phone number, along with other personal information, to switch to another telecom company. By creating a new account in the victim's name, they can reset access credentials to their financial and social media accounts.

Of course, telecom companies have controls and preventive measures to protect against number porting fraud, such as personal identification numbers (PINs) and passwords associated with accounts. However, these measures are still not completely foolproof, and hackers will try to circumvent the protections put in place by telecom companies by linking potential victims' phone numbers with public and hacked information. With this combined data, they may be able to convince a telecom company representative to port the number.

Mobile phone cloning

Attackers can also monitor the radio waves of mobile phone transmissions and clone their own copies of the account onto an unauthorized mobile phone. The cloning process involves copying the unique electronic serial numbers and mobile identification numbers.

Once the information is transferred to the cloned phone, telecom companies cannot distinguish the cloned phone from the original. As always, the first step is to inform the telecom company if any suspicious charges appear on your account.

What to do if you suspect your phone number has been hacked?

If you notice any indicators of a problem with your phone account, such as unauthorized charges, account lockout, slow performance, unexpected verification codes, or even complete service interruption, the first thing to do is contact your service provider and inform them of potential misuse of your phone number. In most cases, the service provider can take the necessary corrective actions, and it does not necessarily mean changing your phone number.

Preventing SIM swapping requires a combination of vigilance and technology (AFP)

You may also need to take additional steps, including ensuring the security of your email and financial accounts, changing passwords, reviewing account recovery settings, and enabling multi-factor authentication via apps whenever possible.

How to protect your phone number in the future?

You must protect your phone number just like any other personal information you keep to yourself. This requires limiting how and where you share your number and associated personal information. Keep it as far from public reach as possible, and be cautious about any activity on your phone service, as well as your financial and social media accounts.

Never answer any calls or text messages from unknown numbers, and if you do answer a call or text and the other party asks for personal information, do not disclose it, and block suspicious numbers.