By default, Twilio trial accounts can only send SMS to numbers that are listed as Verified Caller IDs in the Twilio console. These numbers have to be added manually, and require a verification message before they can receive SMS. This is an excellent feature for development, as it prevents accidentally sending SMS to wrong numbers.
My problem, is that I am developing for a client whose account is already out of trial status. I don't want the software in development to be able to send text messages to any number, because there is a risk of sending dev messages to the client's actual customers. However, we need to be able to send to some numbers for testing. Is there any way to turn the trial behavior back on? That is, can we somehow configure Twilio to only allow sending SMS to verfied numbers, even if it is not a trial account?
If this isn't possible, I think I can query the Outgoing Caller IDs resource from my program to verify the recipient number against the list before sending. However, this puts the responsibility back on my development team, and the possibility for mistakes remains. I'd like to be able to block the behavior at the Twilio level.