Twitter started asking me for my phone number about a week ago to sign in. I did not provide it and complained that I should be able to verify my account with just the email on file. Then a few days ago I could login again, but my account was suspended. All the images on my tweets are blank and the list of people I follow is gone. I have appealed for reinstatement. We'll see how that goes. I was surprised not to see this new phone number requirement for twitter on HN or other sites sooner.