I wonder how Duplex would work if it rings a line powered by Duplex (for example, a business uses Duplex to schedule bookings). Would it just talk to the backen

I wonder how Duplex would work if it rings a line powered by Duplex (for example, a business uses Duplex to schedule bookings). Would it just talk to the backend, or would Duplex talk to the receiving Duplex in the normal scheduling chat dance?