The interview process is a way to clarify the customers expectations as well as for you to have the opportunity to close the first impression door.  What that means is, if you nail the following instruction down perfectly as well as connect on a personal level with the customer, the rest of your call should be smooth sailing.  Think of it as putting closure to the formalities. Don’t mistake that from continuing to be professional, as your professionalism should continue throughout the course of the entire call.