How to Secure Your Phone Number

Your phone number is more than just a way for people to call you. It has become a de facto identity document — used for two-factor authentication, account recovery, identity verification, and communication across dozens of services. When someone gains control of your phone number, they can potentially access your bank accounts, email, social media, and more. Here is how to protect this critical piece of personal information.

Why Your Phone Number Is Valuable to Attackers

Your phone number is connected to:

• Banking and financial accounts — Used for login verification and fraud alerts
• Email accounts — Often used as a recovery method
• Social media — Linked for account security and contact discovery
• Two-factor authentication — SMS codes are sent to your number for login verification
• Identity verification — Many services verify your identity through your phone number

A compromised phone number can be the master key to your entire digital life.

The Biggest Threat: SIM Swapping

What Is SIM Swapping?

SIM swapping (also called SIM hijacking) occurs when an attacker convinces your mobile carrier to transfer your phone number to a SIM card they control. Once they have your number, they receive all calls and texts meant for you — including two-factor authentication codes.

How Attackers Do It

1. Gather personal information — Using people search sites, data breaches, or social engineering to collect your name, address, date of birth, and account details
2. Contact your carrier — Call customer support pretending to be you
3. Pass security verification — Using the personal information they gathered to answer security questions
4. Request a SIM transfer — Claiming they have a new phone and need their number moved
5. Take control — Once the transfer completes, they receive your calls and texts

Signs of a SIM Swap Attack

• Sudden loss of cell service — Your phone shows "No Service" or "Emergency Calls Only"
• Unable to make calls or send texts
• Notification from your carrier about a SIM change you did not request
• Unexpected password reset emails for your accounts
• Unauthorized transactions on financial accounts

How to Protect Your Phone Number

Carrier Security

Contact your mobile carrier and set up additional security:

• Add a PIN or passcode to your account — Required for any account changes
• Enable port-out protection — Prevents your number from being transferred without additional verification
• Remove personal information from security questions — Use random answers that cannot be found through public records searches
• Use a strong account password — Unique to your carrier account

Carrier-specific options:

• T-Mobile: Account PIN + SIM protection
• AT&T: Extra Security passcode
• Verizon: Account PIN + Number Lock
• Google Fi: Account security settings in your Google account

Reduce Your Phone Number's Exposure

Your phone number appears in more places than you might think:

• People search sites — Your number is likely listed on platforms like ActualPeopleSearch, WhitePages, and others. Opt out from these services to reduce exposure.
• Social media profiles — Remove your phone number from Facebook, Instagram, and other profiles
• Data broker databases — Request removal from major data brokers
• Public records — Some records (voter registration, business filings) include phone numbers

Use Authenticator Apps Instead of SMS

SMS-based two-factor authentication is vulnerable to SIM swapping. Switch to more secure alternatives:

• Authenticator apps — Google Authenticator, Authy, or Microsoft Authenticator generate time-based codes on your device
• Hardware security keys — Physical devices like YubiKey that provide the strongest protection
• Passkeys — The newest standard that eliminates passwords entirely

For every service that supports it, switch from SMS-based 2FA to an authenticator app or hardware key.

Phone Number Best Practices

• Use a secondary number for online sign-ups and non-essential accounts (Google Voice or a similar service)
• Keep your primary number private — Share it only with trusted contacts
• Do not use your phone number as a username or display it publicly
• Be cautious about who you give your number to — Every new service that has your number is another potential exposure point

Dealing with Spam and Robocalls

Blocking and Filtering

• Enable built-in spam filters — Both iPhone and Android have call filtering features
• Register with the Do Not Call Registry — Visit donotcall.gov (helps with legitimate telemarketers but does not stop scammers)
• Use carrier spam blocking — Most carriers offer free call filtering services
• Install a call blocking app — Apps like Nomorobo, Hiya, or RoboKiller can filter spam calls

Phone Number Spoofing

Scammers can make their calls appear to come from local numbers or even numbers you know:

• Do not trust caller ID — The displayed number may not be the actual caller
• Do not answer unknown numbers — Let them go to voicemail
• Do not call back unknown numbers that left no voicemail
• Report spoofed calls to the FCC

If Your Number Is Compromised

Immediate Steps

1. Contact your carrier immediately — Report the unauthorized SIM swap and regain control
2. Change passwords on all accounts linked to your phone number
3. Check financial accounts for unauthorized transactions
4. Enable non-SMS 2FA on all accounts that support it
5. Check your email for password reset confirmations you did not request
6. File a report with the FTC and local law enforcement

Recovery

• Request a new number if your current number has been widely compromised
• Update your contacts and accounts with the new number
• Monitor your credit for signs of identity theft
• Consider a credit freeze as a precaution

Your phone number deserves the same level of protection as your Social Security number. Taking these preventive steps today can save you from significant financial and personal damage in the future.