Yup, they usually lock the account once you start using it, possibly using some kind of pattern detection.

Tried it two times in last six months. Once via the Android app and the second time on the website on my laptop. Both accounts were blocked after less than 15 minutes without even doing anything (except following a few accounts which Twitter suggested based on my interests... [0]). Both times they wanted a phone number to unlock.

I tried to contact the support, but they never responded.

[0] different accounts, based on different interests

It's getting even better. I just logged into one of the suspended accounts. Pretty much everything is locked, but without any information about the suspension. It's pretty much "Oops, something went wrong. Please try again later." on everything.

Ok, let's try it with the "Twitter privacy policy inquiries" form (while logged in). Nope, can't submit anything, because of the suspension. So why not have some fun? Just sent a GDPR request via the "suspension appeal" form. Why? For the lulz and to have some legal leverage.

Not even five minutes passed and I got a email. My account is not suspended anymore... WTF twitter?

And there my account sits, a year later. I can't close it because they won't let me do that without adding a number, but I'm not going to add it.

> possibly using some kind of pattern detection.

The pattern of "not having provided a phone number" perhaps?

I wanted to provide them the benefit of the doubt. Probably.