This is likely because of industry regulations around A2P (application-to-person ) messaging that had a due date of August 31, 2023.

It's not just Twilio, you would have experienced this with nearly every SMS API provider. Across the different vendors I work with, I received numerous emails from each one advising me to come into compliance or risk my messages being rejected.

https://help.salesmessage.com/en/articles/6650461-changes-to...

https://www.telgorithm.com/news/10dlc-registration-required/

https://support.referrizer.com/support/solutions/articles/10...