The following steps explain a customer call flow:

1. Driver Application launches call to the Customer from MPP by sending SIP INVITE.

2. SIP INVITE is routed by System Manager towards the Gateway (G/W).

3. G/W places the call to the Customer present outside the enterprise.

4. On successfully connecting to the Customer, G/W completes the INVITE transaction, and MPP plays the desired message to the customer, or gives some call treatment.