3DSC 2.28: Obscure Your Phone Number

Your phone number may not seem like a big deal. You give it out to nearly everyone one – and every service – in your life. I believe that your phone number is more important than your social security number as an individual identifier. Your phone number is linked to your entire digital trail – your public online accounts, the dossiers private data broker have on you, your mortgage information, your medical history, the location of every place you have ever taken your mobile device, and every person to whom you have placed a call or text message, how long the call lasted, and where it originated. Phone companies also typically don’t do a great job of protecting this information. I think you should make ever effort within your power to obscure your real phone number.

Difficulty: Hard
Active Time: 10 minutes (initial setup), repeated interaction
What it Protects You From: Mobile account takover, account linkage

Obscure Your Phone Number

There are several applications and services that will help you with obscuring your number. Selecting one and installing it is the easy part.

Sudo: If you listen to the Complete Privacy & Security Podcast, you know that I am a big fan of Sudo. Sudo is currently an iOS-only app that allows you to create nine personalities, each with an email address and phone number. Each of these phone numbers can handle incoming and outgoing calls over a data or Wi-Fi connection. Because of the versatility of nine phone numbers, Sudo allows extreme compartmentalization. You can use one number for personal contacts, one for business contacts, one two-factor authentication, one for throwaway accounts, and so on. A full article on Sudo strategies is on its way soon. Currently, Sudo is completely free. For more information or to download the app visit https://sudoapp.com/.

Flyp: If you do not have an iOS device, Flyp is the next-best option. Flyp allows you to have up to six phone numbers. With Flyp you get one free number, and each additional number (up to 6) costs $7.99/month or $79/year. Flyp is a distant second to Sudo because Flyp collects much more data than Sudo. For more information visit http://getflyp.com/.

NOT RECOMMENDED: In the past I have recommended Google Voice. I can no longer recommend this service in good conscience.


Choosing an application that offers additional phone numbers is the easy part. Actually making the switch can be really difficult. Begin changing your phone number(s) with online services that you do not receive calls to and from. As you become more comfortable working from Sudo or Flyp, transition more and more of your daily communications. The ultimate goal is to change your existing telephone number completely, and give it out to no one, with the possible exception of extremely trusted contacts who may need to reach you in an emergency.

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