It's been a requirement for a while that you have to have a real (non-VoIP) cell number for doing 2FA. Personally, I hate this idea since getting a VoIP number for 2FA isn't vulnerable to SIM Swapping attacks like my number issued by T-Mobile is. The last time I set up a Twitter account I had to do the "unsuspend me" thing half a dozen times before Twitter stopped insisting on auto-suspending because I smelled like a bot for some reason.