To enable two-step authentication using text messaging (SMS), go to your user profile and click "Add" under the two-step authentication section, then select "Add SMS". Add your phone number and confirm it with the unique verification code sent to you. Store the backup code provided in a safe place, and Stripe will request a code for new devices and periodically for security.

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Before you enable two-step authentication using text messaging, please note that SMS is unencrypted, requires cell reception, and is vulnerable to SIM swap attacks. Once your phone number is known, there is currently no feasible way to defend yourself from SIM swap attacks. Stripe encourages you to use an authenticator app or a hardware security key instead.

If you would like to use SMS anyway:

1. Go to your user profile.
2. Click Add under the Two-step authentication section.
3. Select Add SMS. You will be asked to enter your phone number. Enter your phone number and click Confirm phone number.
4. You will be sent a unique verification code to confirm that we've got the right phone number. Note that it may take a minute or two to receive your verification code.
5. Write down the backup code shown and store it in a safe place.

The setup process is then complete. Going forward, Stripe will request a code if you sign in from a new device, as well as periodically to make sure it's still secure.