If you use your SenderID to send critical notifications and activation OTP/codes and need them to be delivered to everyone even Blacklisted/DND numbers, then you must apply for whitelisting your Sender ID.
Prepare a request with your company letterhead and send it to us with company license and civil id, we will take care of the rest. (Example Letter)
+ Do you offer demo/trial account?
+ What are the requirements for Sender ID registration?