@Steven Paul,
Thanks for writing to our forum.
If you are using Twilio free account, then both sender and receiver need to be verified in twilio (It’s a twilo feature).
Imagine you are registered as a free user and trying to send SMS to another. In this case, you have to verify that number at first to make successful SMS communication.
Let me know if you are a pro user of Twilio but still facing this issue.
Regards.
