Received notification "Impact to SMS Workloads on unregistered US long code" but have no numbers in Pinpoint

We received a warning email notification stating:

Starting August 31, 2023, Amazon Pinpoint will start blocking SMS messages sent using unregistered long codes. If you plan to continue sending SMS messages after this date, you are required to obtain one of the following compliant number types: 10DLC [1] , Toll-Free Number [2]. Note that each type requires a registration process before the number can be activated so we encourage you to start these requests immediately.

The following is a list of your affected resource(s) in the "US long code | Volume of SMS sent in last 30 days" format: 1206984xxxx|0

(note we changed the last four digits of the number in the email to xxxx to anonymize the data)

However, when we go to the Pinpoint console, no numbers are shown at all (see attachment)

May we please ask for some advice how to address the warning message? Thank you.