Mostly ignore things I'm not interested in but it did find somethings.

It turns out that Twilio is quite expensive, more than I willing to pay
for this service. So I'm going with MessageBird.

AWS' SMS delivery has been unreliable to say the least. Replace it with
Twilio but that's more complex:

- A new Lambda function to send SNS messages as SMS messages with
  Twilio.
- Add the function as a subscription to the SNS topic.