Twitter announced this week that it will make SMS-based two-factor authentication a paid feature of the service starting March 20, 2023.

“Instead of only entering a password to log in, two-factor authentication (2FA) requires you to also enter a code or use a security key,” a post to the Twitter blog explains. “Instead of only entering a password to log in, 2FA requires you to also enter a code or use a security key. This additional step helps make sure that you, and only you, can access your account. To date, we have offered three methods of 2FA: text message, authentication app, and security key.”

Starting immediately, Twitter will no longer allow new customers to use 2FA via text message because it’s insecure. And starting March 20, it won’t allow any non-paying customers to use text message-based 2FA; this feature will instead require a Twitter Blue subscription.

Non-subscribers will need to disable text message-based 2FA and enroll using an authentication app or security key instead. You can learn how to do that at the Twitter help center.