7 Times When It’s Not OK To Give Your Phone Number


Did you know that 93% of cyberattacks originate from devices on a network? Most of these attacks were successfully executed against mobile devices. Your smartphone is by far the most vulnerable device you use. Yet, most people give away their phone number without a second thought. Here are the 7 times when it’s not OK to give your phone number:

  1. Account sign-ups and profiles
  2. Two-factor authentication
  3. Online forms and surveys
  4. At store checkouts and rewards programs
  5. Work-related calls
  6. People that are not close friends or family
  7. Careless friends and family

Let’s walk through each of these situations, and I’ll explain why it’s not a good idea and what you can do instead.

Sign-up page with people on devices in front.

Do Not Give Your Phone Number For Account Sign-Ups & Profiles

A phone number should be one of your most guarded pieces of personally identifiable information (PII). However, many people enter their number on a website, app, or social media platform that requests it without thinking about the consequences.

Another thing that can happen if you post your number online is that your number can be sold on the dark web. This means that you will be receiving spam phone calls, phishing messages, and spoofing texts. Remember, the internet is full of scammers keen on social engineering attacks when it serves their interests.

What if you have a business website and want your customers to reach you easily? You can decide to have a separate number for your business website. This is because advertisers and marketers alike will be sending you endless text messages and ads on your cell phone.

Do Not Give Your Phone Number For Two-Factor Authentication

With most people incorrectly using and managing passwords, I always recommend using two-factor authentication to secure users’ accounts.

Unfortunately, many companies take the easy way out when adding multifactor authentication to their websites. The company will simply send a one-time use verification code to an account holder’s phone via SMS text messages.

While this is better than nothing, 2FA over text message is the least secure method to implement this crucial second layer of security. Several attacks can intercept SMS messages to your smartphone, receiving the one-time password (OTP) ahead of or instead of you.

Please do not give your phone number to a company for two-factor authentication…unless it’s the only option for multifactor protection.

You have two better alternatives to SMS based two-factor authentication:

  1. Use a two-factor authentication app like Aegis Authenticator for Android or Raivo OTP for iOS.
  2. Hardware keys like a YubiKey or Nitrokey
Woman filling in an online survey on a laptop.

Do Not Give Your Phone Number When Filling Online Forms & Surveys

As an online user, you must have filled out online forms. It could be when paying using credit cards, using mobile phone applications, doing surveys, or transacting online.

However, each time you did so, you exposed yourself to online fraudsters keen on getting your credit card details. When submitting your phone number on an insecure website, you risk malicious people stealing your data and using it to extort money or commit fraud.

Is there a way to know when it’s not okay to give your phone number when filling out forms? The following are the red flags to watch out for if you don’t want to be a victim.

Avoid opening links sent to your email requiring you to provide your information, including your phone number. Cybercriminals can clone legitimate websites, which means if you click on those links and fill in your details, you are downloading malware that will harvest your data.

Read the privacy policy of a website or a mobile phone application to know exactly what you are agreeing to. Google requires that all apps that collect personal data have a Privacy Policy. What is contained in a company’s Privacy Policy?

  • What information the company will collect.
  • How the company will use your information.
  • Whether it shares customers’ data with third parties.
  • Changes to Privacy Policy. Scammers do not provide such information.
  • Look for a secure protocol. Each time you receive an email and notice that the website does not have an ‘s’ at the end of HTTP, avoid that website like the plague. The reason is that your connection is not secure, and scammers will likely steal your information. On the same note, a website with no lock icon on the left-hand side of the search bar is not secure.

What about giving your number to random people, perhaps strangers who helped you pack your groceries?

Do Not Give Your Phone Number At Store Checkout Or For Rewards Programs

It could be you are at the grocery store waiting to receive a discount after doing some shopping when the shop attendant asks for your cell phone number. Without a moment’s hesitation, you give out your number and watch as they key it in on the computer.

The stores use such data for multifold purposes. These include selling such sensitive information to third parties and creating targeted ads based on your purchase history.

Contrary to what you may think, stores are usually targets of scammers. They store their customers’ account information using third-party tech cloud companies that are open to hacking. This is one scenario when it’s not okay to give your phone number.

When hackers access your information, they may go ahead and take out a loan in your name and even go as far as opening credit cards. They can use your data to fool automated systems into thinking that you are doing the said transactions.

Similarly, once they have your private information, scammers do what is called spoofing. Here, you will receive a call from your trusted store asking you for some personal information. You will trust the source because the caller ID displayed will be from the store. The article how to avoid email spoofing has handy tips on how to counter spoofing.

With that in mind, don’t feel guilty when you turn down the cashier’s request to give out your phone number. After all, giving your number at the checkout is optional.

Man in suit pointing angrily at his cell phone.

Do Not Give Your Phone Number For Work-Related Calls

It is not advisable to give your personal or home number to colleagues or your organization, especially if you feel they will intrude on your off-hours. Nowadays, the line between work and personal life is blurred, especially since everyone has a smartphone.

If your company gives you a work phone because of the nature of the business, then that is understandable. However, receiving text messages on your phone number from work during your family time is not something to make you smile.

Sometimes, your company might send you out for work assignments, workshops, and seminars. It is sensible to leave your company phone number in the visitors’ book. Also, your company business card should have your company number instead of your cell number. After all, you want to safeguard your privacy at all costs while protecting your job at the same time.

Do Not Give Your Phone Number To People Who Aren’t Friends Or Family

Giving numbers to strangers we meet in our day-to-day lives might seem innocent. However, have you ever thought of the implications when your number lands in the wrong hands? Since a cell phone is your most personal tool, you have a good reason to ponder that question.

Your mobile phone is connected to applications and any online transactions, be it at the grocery store or pharmacy. So, how do identity thieves, hackers, and impersonators use your phone number?

Hackers can use your mobile phone number to find your location, hijack your mobile phone, and even use any of your accounts. They can also access enough information about your family members, which allows them to send phishing messages to them.

Having gone digital, you might have been complacent by having weak passwords to different accounts and logging in to websites via insecure connections. Therefore, cell phones will be the key to the scammers getting your details.

What can you do if you have already given your number to a non-friend? The simplest thing you can do is to block them if they call you and you believe they are scammers. You can also change your passwords if your number is linked to various online accounts.

Do Not Give Your Phone Number To Friends Or Family That Are Careless

Even some of the closest people to you might not be as protective of your phone number as you are. They might give it out to other people without thinking twice about it. Therefore, when it comes to sharing your phone number with friends and family, it is essential to proceed with caution.

There is also a real possibility that one of your friends or family members might be careless with their privacy settings. When they sign up for platforms, they allow the mobile apps to sync all their contacts and store the mobile phone numbers on their servers. While this may not seem like a big deal, it can be quite dangerous. If the platform were to ever be hacked, or if the company were to sell user data, then all of those contacts (including yours) would be at risk of exposure. 

Also, as any savvy internet user knows, a single post online can be the beginning of a long and devastating nightmare. Let’s not underestimate the privacy risk posed by family members and friends who post excessively online. For all we know, a simple slip-up can occur where they accidentally post your phone number on their public profile for the whole world to see. Once that happens, you can expect to start receiving constant and annoying robocalls, scam calls from unknown numbers, and even more serious threats like identity theft.

Understandably, it may not always be possible to avoid giving your phone number to friends and family. Still, it is unequivocally important to be selective. It might be best to refrain from sharing your number with someone you know is not particularly mindful about their online privacy. The same goes for people known to excessively post online — the risks simply outweigh the benefits.

Mike Chu

Mike is a web developer and content writer living as a digital nomad. With more than 20 years of devops experience, he brings his "programmer with people skills" approach to help explain technology to the average user. Check out his full author bio by clicking here.

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