(Photo: Getty Images/Thinkstock)

Recently, AT&T surprised everyone when it added a new option to its GigaPower fiber Internet service: privacy. Yes, for just $29 more a month AT&T promises it WON'T sell your search and browsing history to advertisers. How generous.

While there's still some doubt about how private your information is even after you pay the $29, at least AT&T is being honest about how it finances operations. The truth is, the major cellphone carriers are more than happy to sell your information to advertisers and serve you targeted ads over their networks.

I'm going to tell you how to stop them, and at the end I'll discuss other ways carriers and advertisers are working to get your information.

iPhone

If you're an iPhone user, you need to go into Settings, and then tap Privacy. Scroll all the way down to Advertising.

You'll see a button labeled says, "Limit ad tracking." If it's not showing a green color, slide the button so that it shows green. This will stop ad companies from tracking what you do with your phone and serving up targeted ads.

Right underneath that setting, by the way, you'll see the "Reset Advertising Identifier" option. Tapping on that will zero out the anonymized identifier linked to your personal data on Apple's servers.

In other words, to trackers you'll appear to be a new user. This can make it more difficult (but not impossible) for advertisers to build up a profile on how you browse.

Android

To turn off the Google "AdID" system, you don't go to your Android phone settings, but your Google Settings app. You might have to look under your full list of apps to find it.

Once you're in Google Settings, tap the Ads link and then tap "Opt out of interest-based ads." You can also see your advertising ID and tap "Reset advertising ID" to make a new one. This will make you look like a new user to advertisers.

Ads aren't the only way you're tracked on your phone. Google and Apple might be tracking your searches. Use this search app instead to make private searches

Windows Phone

To turn off Personalized ads in Windows Phone, go to Microsoft's ad opt-out page and under "Personalize ads whenever I use my Microsoft account" click "Off."

You will need to be signed in with a Windows account to do this. Make sure you sign in with the same account you use on your Windows Phone. This also turns off personalized ads for Internet Explorer in Windows 8.

The future of tracking

Of course, carriers are working on ways to track you that you can't stop. Verizon and AT&T have experimented with "supercookies" that let any website know who you are when you visit.

AT&T eventually dropped the idea when customers complained, but Verizon still does it. You can opt out at https://www.verizonwireless.com/myprivacy/ , so Verizon won't track your information or show you targeted ads. However, Verizon does still add the supercookies to your browsing, which can give away your identity to websites or hackers.

Tracking and selling your information isn't just a problem with cellular carriers, though. There are ways every ad company can track where you go online. Click here to protect your privacy against online advertisers