Avast Academy Security Phishing What Is Phone Number Spoofing and How to Stop It

What Is Phone Number Spoofing and How to Stop It

Phone number spoofing to disguise caller IDs is a growing phenomenon, and the problem isn’t limited to the receiving end of spoofed calls, because your number can be stolen and used by scammers to initiate spoofing attacks. Learn how to identify the warning signs that your number’s been hijacked by scammers and how to block spoofed calls. Then, get a mobile security and privacy app to protect your phone from malware and other online scams and threats.

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Written by Oliver Buxton
Published on September 10, 2021

What is phone spoofing, exactly?

Phone spoofing is the use of fake caller ID information to mask the true source of an incoming call. Scammers typically spoof phone numbers in order to appear to be from a particular location or organization, increasing the chances of people picking up and falling for their cons.

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    Caller ID spoofing is one of several kinds of spoofing used by scammers and cybercriminals. As with email and IP spoofing, the basic social engineering principle remains the same.

    By masquerading behind a spoofed local or well-known number, the caller attempts to impersonate a trusted contact or authority. Typical phone spoofing goals include acquiring sensitive personal information or scamming the victim out of money.

    How to stop someone from spoofing your number?

    Since spoofing services typically generate numbers randomly, there’s no surefire way to prevent a phone number spoofer from using your caller ID. But there are still steps you can take to help stop your number from being used by scammers to carry out illicit activities using social engineering tactics.

    • Don’t share your phone number or any other personal data with anyone unless it’s necessary.

    • Be wary of online prize-draws and sweepstakes.

    • Read terms and conditions carefully.

    • Make sure consent boxes allowing your data to be shared or sold are left unchecked.

    How to tell if your phone is spoofed

    There are a number of telltale signs which indicate that your number is being spoofed. If your spoofed phone number is being used to spam lots of potential victims, you may notice:

    • Incoming calls or text messages responding to communications you didn't initiate.

    • Calls or messages from people asking who you are.

    • People you don’t know calling or texting you asking to stop bothering them.

    • Incoming calls that appear to be from your own phone number.

    Can you find out who spoofed you?

    Discovering whether your phone number’s been spoofed isn’t easy. And since VoIP service providers allow callers to configure custom caller ID information, finding out who is spoofing your phone number can often be very difficult.

    If you do ever get spoofed and the attacker tries to further compromise your phone, using a strong Android anti-malware app or iPhone security software can make sure your device stays safe.

    What to do if your phone is spoofed

    If you suspect that your caller ID is being improperly used as a spoofed phone number, you should take the following steps to help secure your privacy and security:

    1. Record a new voicemail message: This will make callers aware that they might have been targeted by a phone number spoof, and that you are not the true source of the nuisance or scam calls.

    2. Block all unknown numbers: Use an app or your phone’s settings to temporarily block or silence all incoming calls from numbers that aren’t in your contacts.

      Selecting Silence Unknown Callers in iPhone settings to prevent further spam calls.
    3. File a complaint with your local authorities: If you’re in the US, the FCC can investigate consumer complaints of phone number spoofing, and hopefully clamp down on unlawful practices. Report a complaint to the FCC here.

    How to stop spoofed calls to your device

    Stopping spoofed calls — and the risk and annoyance that comes with them — relies on preventing spoofing services from using your number, as well as blocking and reporting scam calls you receive.

    Here’s how you can stop phone spoofing:

    • Avoid online competitions or sweepstakes: The internet is flooded with dodgy contests and fake surveys designed to soak up your personal information. Even some legitimate competitions sell your data to third parties.

    • Don’t answer calls from unknown numbers: Incoming calls with blocked or unfamiliar numbers should raise red flags. By refusing to pick up, you deprive would-be scammers the chance to deceive you.

    • Report unwanted calls to local authorities: If you’re in the US, any suspect or unwanted calls should be reported to the US’s FCC (Federal Communications Commission), which investigates consumer complaints of fraudulent phone spoofing. Elsewhere, find your local office to report fraud.

    • Manually block spam numbers on your device: Regardless of whether the number has been spoofed or not, calls originating from any caller ID can be blocked by your phone to prevent further hassle or abuse.

    Many of these steps will not just combat phone number spoofing, but also help to fight robocalls. SMS-based spoofing scams can be countered by manually blocking the spam messages on your device.

    How to block spoofed calls on Android

    Spoofed numbers can be blocked on an Android device the same way as any spam caller or unwanted contact.

    1. Open your Phone app on your home screen and find the Settings menu.

      Locating the settings menu in the Phone app for Android to block a phone spoofing contact.
    2. Tap Block numbers. If your phone has caller ID and spam protection, enable this too.

      Using the Block numbers and Caller ID and spam protection features to stop phone spoofing on Android.
    3. Find the number you want to block, either by typing in the number, or locating it in your Recents or Contacts lists.

      How to stop caller ID spoofing by manually blocking numbers on Android.
    4. After selecting the number, hit Done or Block to stop that number from contacting you again.

    Blocking nuisance callers or caller ID scams is a quick and easy fix for the immediate problem, but isn’t a long-term privacy and security solution. From banking Trojans to snooping spyware, mobile-specific threats grow by the day and require comprehensive and proactive protection.

    Avast One for Android defends against the full range of mobile malware used by hackers and scammers, keeping your phone protected in real-time with advanced threat-detection and privacy-enhancing technology.

    How to block spoofed calls on iPhone

    Stopping caller ID spoofs via your iPhone settings is quick and easy. Here’s how:

    1. Open the Phone app on your home screen and tap Recents to display your call history. Then hit the Info icon next to the number you want to block.

      Stopping spoof calls on iPhone by blocking contacts via the Recents tab in the Phone app.
    2. Tap the Block this Caller option at the bottom of the screen.

      How to prevent spoofed phone calls by blocking a caller on iOS.
    3. Finally, hit Block Contact and your iPhone will block further incoming calls or messages from that number, spoofed or otherwise.

      Selecting Block contact prevents your iPhone from receiving calls or messages from the spoofed phone number.

    Avast One for iOS is tailor-made for securing your privacy on iPhone and iPad, with powerful security and privacy features that guard your passwords and encrypt your photos. And it features a powerful Web Shield to make sure you don’t fall victim to malicious websites.

    Why is phone spoofing dangerous?

    Spoofing cell phone numbers may not seem like a serious threat. But by altering caller ID information, scammers can pretend to be from reputable organizations, manipulate people into divulging sensitive personal data, and defraud them out of thousands of dollars.

    Deceptive spam calls often purport to be from the IRS and try to intimidate people into making bogus back-payments for taxes. Another common grift is the tech-support scam, where the spoof caller claims to represent a well-known company before proceeding to infect your computer with malware, such as ransomware, or steal your credit card details.

    Why do phone companies allow spoofing?

    Spoofing a phone number isn’t illegal, and there are plenty of legitimate reasons why an individual or organization may choose to do so. Spoofing has long been used by businesses to make calls from an official number on various devices. Today, it’s increasingly used to mask the personal information of gig workers and customers in the sharing economy.

    Phone spoofing is only unlawful if done with malicious or fraudulent intent. Unfortunately, the spread of VoIP (Voice over Internet Protocol) technology has made it even easier for scammers and robocallers to spoof numbers and leverage phony caller IDs for nefarious ends.

    What are the legitimate reasons for phone spoofing?

    Although phone number spoofing is usually associated with scams and irritating telemarketing calls, there’s a long list of legitimate — and even mundane — reasons why individuals and organizations would want to know how to spoof a phone number.

    Here are some of the many legal uses of phone spoofing to manipulate caller ID info:

    • Law enforcement: Police and other enforcement agencies commonly use phone number spoofing to contact people covertly.

    • Healthcare: In fields where client confidentiality is paramount, spoofed numbers help to preserve privacy.

    • Helplines: Phone spoofing allows vulnerable people to reach out for help discreetly.

    • Journalists: Sources may wish to communicate with journalists without disclosing their location or identity, and vice versa.

    Protect your phone against scammers with Avast

    Phones are a potential goldmine for hackers seeking access to your finances, private information, and other sensitive data. With Avast One’s cutting-edge technology that combats the latest mobile threats, you’ll have one of the world’s most powerful cybersecurity apps watching your back 24/7.

    Get comprehensive security and privacy protection today against malware and other online threats.

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    Oliver Buxton