@Santhosh Nethaji Thanks for reaching here!
As its mentioned in the rejection response- suggest you to send your application again, but this time include a valid URL that shows proof that you've gotten permission from customers to send them messages. This can be a screenshot or a mock-up of the webpage or app where customers give their consent to receive messages from your company.
Refer to this Official doc-https://learn.microsoft.com/en-us/azure/communication-services/concepts/sms/sms-faq
Further if above does not help- suggest is to create support ticket.
Hope this helps, Let us know.