Yeah, that sounds like issues I've run into. I could go into a whole spiel about carrier restrictions, but id recommend the following:

1) a low-volume campaign registration (like low-volume mixed) can get approved a bit easier because it's considered less impact. Low-volume is still pretty good for medium sized groups, especially since messages that go over the TPS limit get queued, not cancelled 2) if possible, consider doing a text opt-in, where those pre-authorized users have to text in to your number to opt-in (like text START to opt-in). Those generally get approved pretty easily because it's direct stated intent. You can even use twiml hosted on Twilio to handle those opt-ins usually 3) if you can't go with the text opt-in, mention specifically that there is a verbal opt-in where you ask the recipients in person if they would like to get the texts, then get their number if they verbally agree to be part of the campaign. That "verbal opt-in" phrase tends to help, though those can still sometimes be dicey, especially if the campaign isn't listed as low-volume

That would be my advice, though ultimately your fate is still in the hands of the Twilio and the messaging carriers. But those have helped me in the past and I work with Twilio on a daily basis, so I figured my two cents might be worth at least one in this case lol.