SNS is not delivering text message to particular mobile carriers since a few days ago

I have a toll phone number in AWS Pinpoint (registered and in production mode) to send Transactional messages and since a few days ago our clients in Costa Rica are not receiving the messages (however in October the messages arrived successfully). In my SNS dashboard the SMS to Costa Rica are in Sent state (we contact in Costa Rica with a Mobile Phone carrier and no restrictions were detected in our clients phone numbers). Where is the point when the flow is broke? or I have to pay to AWS for a technical support plan to report this issue in the infrastructure, a wrong behavior that is not a bad implementation of the user, is a service that a day starts to work in an unexpected way? Also some other users in this forum are reported similar issues in the last days.