A caveat when using Amazon SNS for sending SMS
The default maximum spend limit is USD 1.00 which is good enough for testing but problematic once you go into production.
The kicker is you need to contact AWS Support to increase it, which takes up to 24 hours for them to act on, unless you’re on one of their paid support plans.
And one more thing:
Please note, it can take up to 7 days for your requested increase to be implemented.