Is it possible to create a vpn tunnel so that the data is not forwarded to the public? I am using an Asterisk server.

Yes, it's absolutely possible to set up a VPN tunnel for secure SIP traffic between your Asterisk server and Vapi. a. Set up VPN tunnel between your network and Vapi's SIP gateway b. Configure your Asterisk server to route SIP traffic through the VPN c. Update SIP trunk configuration to use private IP addressing To help you further I need more specific confiiguration details in your asterisk setup.