How to spam a cell phone number

We are no longer supporting IE (Internet Explorer) as we strive to provide site experiences for browsers that support new web standards and security practices.

We recommend our users to update the browser.

Techlicious editors independently review products. To help support our mission, we may earn affiliate commissions from links contained on this page.

While it may not feel like it, the number of robocalls has dropped below its peak in 2019. In March 2021, there were nearly 5 billion robocalls. Last month, there were 3.9 billion calls, according to YouMail's Robocall Index. That's still a lot of calls. 

You may have registered on the FTC’s National Do Not Call Registry and maybe you know regulations exist that limit the ways debt collectors and companies selling things can pester you on your cell phone. But even if you have these safeguards in place, the calls keep coming. So how do telemarketers get your phone number anyway? You might be surprised.

1. You overshare your number

Anytime you fill out a form and give out your phone number – whether it’s a contest entry, a warranty registration, a signup form for an online service, what you include on your social networking profile – you’re opening yourself up for solicitations. Or, think about how many retailers have your number because you want loyalty points to score discounts or in-store credit.

Even putting your phone number in your email signature can put you at risk. As can giving your number to your dentist for appointment reminders or favorite food delivery service to get a "convenient" text notification. Even using two-factor authentication (which we hope you do!) can require you to give up your phone number.

If you enter your number on a form or online, there's a chance that your number will end up in someone else's hands. 

2. You accept Terms of Use without reading or understanding them

A growing number of mobile apps – things like flashlight utilities or games – are really only interested in harvesting your personal information and selling it. So make sure you read the Terms of Use or Terms of Service. And check to see what apps want to access when you install them. Apple provides a clear listing of the data that's used to track you and the data that's collected and linked to you in App Privacy section for each app in the App Store. By July 2022, Android developers are required to provide privacy information for their apps in the Google Play safety section, which includes how user data is collected and handled.

3. Big data has killed privacy

We live in an age where computers are so smart and fast they can crawl the web and look at billions of data points instantly. In a blink they can look at everything you like, post, or tweet. They can mine census data and other public records, such as how much you paid for your house and whether or not it was ever foreclosed upon. Just search for yourself on PeekYou – you’ll be amazed at the number of companies that claim to have information about your family, income, phone number and much, much more. (Check out our guide to removing yourself from people search services.)

Again, the more information you share online, the easier it’s going to be for someone to get your mobile number.

4. Technology can dial zillions of random numbers like it’s nothing

We’ve all received calls that don’t have another human on the other end. Not only is the call robodialed, but the process of finding your number is automated as well. Dialing devices can figure out and call all possible phone number combinations, including unlisted and mobile numbers.

5. Automatic Number Identification can sabotage you

When you call 800, 888, and 900 numbers your phone number can be captured by a system called "Automatic Number Identification" or ANI. ANI automatically identifies and stores your number and matches it with other online digital markers associated with you.

6. The credit bureaus give away your information

Before you get mad at them for spilling so much of your personal information, remember – you’re the one who agreed to sign up for that department-store credit card so as to receive 25% off.

7. Charities take all the fun out of being philanthropic

Some charities hire third-party telemarketing companies to collect funds on their behalf. Telemarketers keep a percentage of whatever they collect, turning over the rest of your donation to the charity. However, the telemarketers also keep your personal information, from which they can profit exponentially as they sell and resell it to other telemarketing companies.

What to do about it

First, be smart about accepting Terms of Use when it comes to apps you’re downloading onto your smartphone. Does a flashlight utility really need access to your call logs?

And, while some telemarketers don’t heed it, many do – register your number on the National Do Not Call Registry (Do Not Call registrations never expire). Note that if you give your cell phone number to a business, they can call you for up to 180 days after even if you’re on the Do Not Call Registry

[Editor's note: Canada has its own Do Not Call registry]

Use a burner or alternate number if you absolutely must sign up for a loyalty program or contest. And there’s simply no reason you need to post your phone number on Facebook or other online profiles. The people who you want to hear from already have your number or can email you to get it.

Also, make sure spam call blocking is turned on and consider using an app that identifies spammers when they call. I like Call Control for Android, Hiya or Truecaller for iOS, and Nomorobo for your landline phone. Alternately, get a Google Voice number. It has a good screener and you can block numbers.

Finally, don't answer calls from numbers you don't recognize. A real person will leave a message or call you back. And don't get taken in by numbers that look familiar. Increasingly, scammers are using a trick called number spoofing to fake a number with the same area code and exchange as your phone number.

Updated on 5/13/2022 with current state of robocalling and new ways to stop telemarketers from getting your number.

[woman screaming into phone via BigStockPhoto]

For the past 20+ years, Techlicious founder Suzanne Kantra has been exploring and writing about the world’s most exciting and important science and technology issues. Prior to Techlicious, Suzanne was the Technology Editor for Martha Stewart Living Omnimedia and the Senior Technology Editor for Popular Science. Suzanne has been featured on CNN, CBS, and NBC.

How do I become a spammer?

How do you text spam?