All about WhatsApp Business API
1. Can you call the Whatsapp number, that’s already registered to use Whatsapp Business API?
If you place a WhatsApp call to your number, it will appear to be invalid.
2. If your end-user deletes a message, would you be able to find out?
As of November 2019, there’s currently no existing feature available in WhatsApp Business API that can detect messages being deleted.