Twitter has blocked Google Voice numbers for 2FA

Twitter seems to have blocked the use of Google Voice numbers for text-based two-factor authentication (2FA). The company hasn’t officially announced this policy change but it no longer allows users to register a Google Voice number for 2FA. The social media platform has also stopped sending 2FA codes to previously registered Google Voice numbers.

For the uninitiated, Google Voice is a voice over Internet protocol (VoIP) telephone service available to anyone with a Google account. It gives you a phone number for calls, texts, and voicemails. The way this service works make it a preferred authentication tool for bots. Many companies don’t allow the use of such virtual numbers for text-based authentication. Twitter is now joining this ever-growing list. This could be part of Elon Musk’s crackdown on bots on the platform.

Twitter blocks Google Voice for 2FA

According to a 9to5Google report, Twitter started implementing this change last week without notifying users. The publication found that Google Voice numbers abruptly stopped 2FA codes from the social network. When signing in on a new or unrecognized device where 2FA is required, Twitter showed a blank box on the screen with no error message. Users had no idea what was happening.

The publication later discovered that the problem was Google Voice. Twitter had dropped support for text-based 2FA using the VoIP service, locking users out of their accounts. Users already logged in on another device could disable “Text message” 2FA from Settings > Security and account access > Security > Two-factor authentication to login on to new devices. They could also register with another carrier. But others are out of luck.

According to the report, trying to re-enable the same Google Voice number for 2FA now returns the error message: “We cannot currently register this phone number”. Meanwhile, registering with a new Google Voice number says: “This phone number can’t be registered. Try signing up with email instead”. Once again, Twitter doesn’t tell what’s the problem. It would be better if it did, so genuine non-bot users could switch to other numbers.

Google Voice doesn’t appear to be the only telephone service Twitter has blocked for 2FA, though. The company has reportedly blocked around 30 mobile carriers globally, impacting many genuine users using those numbers from those carriers for 2FA. Musk says those carriers were “gaming the system” by sending bogus texts to inflate numbers and make money off Twitter. Hopefully, the company will work out a way to unblock genuine users and only remove individual offenders.