If you lost your phone and expect to get a new one on the same number, it is usually best to wait till you get the phone and install the Authy App, rather than initiate a security check here which will lock your account for several days.
If you travel often or if you have temporarily left your country, use the Authy App on iOS, Android or Chrome so your security codes still work, even if you change your cell phone number temporarily or don't have internet access - the apps even work offline.
If you have changed your phone number (and/or email address), you should update your Authy app as soon as possible, because your phone number (and email) will be used to reinstall the app if you lose your phone. If you have changed your number and also have a new handset and are now locked out, see below - you will need to complete a security check.
If you still have access to your Authy app:
If you still have access to your mobile phone or computer where you have Authy, you can go to the upper right of the app, Settings > My Account and click your phone number. Your phone change will be processed after an email approval security check.
*Note: This is a screenshot of the Android Authy App. Your actual settings page may look different.
If you have a new number, and also lost your phone or no longer have access to the Authy app:
Open https://www.authy.com/phones/change on your browser and enter your new and old phone numbers.
Note: Phone changes require additional security checks and will be processed between 48 to 72 hours.
If we find unusual information in your request, we might ask for your ID and other questions regarding your usage of Authy to verify your identity and ownership of the account.