No. Short codes should be able to receive incoming messages from any mobile numbers within their reach. This is because a short code must always be able and ready to respond to required keywords like STOP and HELP.

For example, a United States short code can reach numbers on most US mobile carriers, so it should be able to respond to messages from those users as well.

Notice: Deliberately blocking any messages or senders on a short code creates a compliance risk and is not permitted.