I've hit the same issue recently, with SMS refusing to send, and this is after the code was working fine for 2 years. Everything looks good and I receive a Success status, but nothing gets delivered to the phone. After much back and forth with AWS it turns out that a proper registered Sender ID is now required in the UK (you can register one of these in "AWS End User Messaging > SMS" as opposed to "Amazon SNS"). For the first time, I was able to successfully send an SMS via the console. I am now trying to update my code so that it sends a request through the correct channel, picking up the registered Sender ID.