Receiving SMS to Pinpoint phone number from a short code number

Hi.

Did you see why you couldn't receive the SMS when you used the shortcode?
You can get the cause of failure from record_status for details by receiving the SMS event.

https://docs.aws.amazon.com/pinpoint/latest/developerguide/event-streams-data-sms.html

Sending SMS is subject to various restrictions depending on the country and regulations.
After understanding the cause of the failure, it is necessary to consider whether countermeasures are possible or impossible.

Do you have enabled 2-way SMS for your short code?