How to protect yourself from phone number recycling

by Burton Kelso, The Tech Expert


If you're in the process of switching phone numbers, you might want to take a minute or two to read this to make sure you prevent criminals from taking advantage of your old number. When your old phone number is disconnected, it doesn't simply vanish. Instead, it enters a process known as phone number recycling, a standard industry practice that reassigns inactive numbers to new users. 

This may seem like a good solution, given the limited number of available phone numbers, but this process has given rise to a significant and often overlooked cybersecurity threat, leaving previous owners vulnerable to account takeovers, identity theft, and privacy breaches.

Here's what you need to know:

In today's digital world, many of the online accounts and real-world services you use require your phone number for verification, and in some instances, the means to recover your online accounts. When you deactivate (or switch) your number, but forget to disconnect all your accounts with this number, your mobile carrier will recycle this number and assign it to a new user. When this happens, it's possible for the new user to be able to access your accounts.

Mobile carriers protect against this problem by enabling a “cooling off” period in which your old number isn’t assigned to anyone. This process typically lasts for 45-90 days. The purpose of this is to allow you time to disconnect any associated services that are associated with your old number. This inactivity period usually allows most people to associate their online accounts and services to their new number, but it always effective because most people fail to remember that they've associated their old number to the large amount of online and offline services they are enrolled in or use.

Once your old number is recycled, the new owner may be able to impersonate you, hack into accounts using SMS or text message recovery methods for online accounts, and access sensitive information about you. To make matters worse, criminals and hackers actively search for recycled numbers by comparing available numbers with or analyzing the sequential number blocks. They then exploit the number for malicious attacks. In many instances with online accounts, it's better to use your email or a unique user name for account credentials, but that's not always possible.

Here’s what you need to do to keep your accounts and information safe if you intend to switch your phone number:

• Remove your old phone number from all your accounts for account recovery and 2 Factor Authentication. Log in to all of your accounts and view account details to see if your number is associated with it in any way.
• If you use a password manager, verify you haven't used your phone number as the account login for your online accounts.
• If you have a Google account, you can open the connected apps page to see services/apps you signed up for. For Facebook signups, check its Apps and Websites page.
• Messaging apps like WhatsApp, Signal, and Telegram that depend on a dedicated number to function usually offer a way to properly delete or change the number. Make sure you go through the official method to switch to the new number or delete the account. ​