Is the on-hook SMS service available? What's in it?

The "on-hook SMS" service is an active push service for corporate advertising SMS.

After the fixed-line number applies for this service, the user can log in to the on-hook SMS platform to set up advertising SMS messages. When the other party calls the fixed-line number, the user can receive the message based on the previous connection status (including connected, no response, busy, etc. Dial status), send different advertising SMS content. (Can be received by China Telecom, China Mobile, and China Unicom mobile phone users)

Note: The character limit for on-hook text messages is 70 characters