SAP MARKETING CLOUD: SMS Campaign failures

Hi,

We are executing SMS Campaigns however all of our messages are failing. We have tried different target groups ranging from 10k to 500k, however, every time we have tried we get a 0% delivery rate. All of our messages fail. This problem has come up recently, about a month ago when we were executing SMS Campaigns they were working just fine. If anyone could please help us identify the root cause behind this issue it would be greatly appreciated.

Thank you,

Ali