I had the same issue with Twilio, they couldn't send anything to my number because of the prefix. After many emails, they finally got it working - then two weeks later it was broken again and I simply gave up.
We have been using Twilio and we're sending them hundreds of dollars a month. I'm about to drop it because of their 2FA requirement. Either they accept customers that know how to manage passwords or they don't. I don't give my phone number to ANYONE any more.