I tried making a Twitter two months ago because I was having trouble with my phone and needed to access T-Mobile's social media-only support team.
Within five minutes of making the account, I was banned for "suspicious activity" and required to enter my phone number "for security purposes". But the only reason I made the account is because my phone wasn't working...
Emailed support and was told that they could not make an exception for me because I had broken some vague unnamed rule. Then I said the magic words, "This is clearly a ploy to collect phone numbers for data aggregation purposes," and within the next 24 hours my account was unlocked, accompanied by a very salty and accusatory email.