"Companies depend on sales consultants to establish trust between clients and companies through their marketing, interpersonal, and customer service skills. Expect to draw heavily on previous experience during an interview. Popular questions ask about situations in which you have changed a client's mind or demonstrated strong interpersonal skills during challenging times. You may also have to demonstrate your sales skills by pitching a product to the interviewer."
If you don't know anything about the cell phone, tablet (ect) the customer is talking about what do you do?
"You could try and persuade them over to a product that you do know something about, read along and point to the information on the box or display, so you both know what the product is about."