Late last ever, they started sending me warning notes insisting that I fill out all kinds of paperwork for my "business" if I wanted to continue sending SMS messages. None of the paperwork made any sense for a hobbyist, but they insisted. It was clear that this requirement was coming from outside of Twilio, so I wonder whether it was the result of earlier discussions with the FCC. Since I don't use the Light Phone any more (couldn't do without a camera), I just turned off SMS delivery rather than deal with all the new bureaucracy. But I still use them for another hack: I can call a Twilio number and leave myself a message, which they will then deliver to a hook on my web server, along with a transcription.
I'm impressed with Twilio technically, and I can sympathize. I wouldn't want to be caught between the FCC and a bunch of SMS spammers, especially if the spammers were customers.