Answer:  This is really a time management issue.  I have a hard time imagining why you would need to receive seven or eight calls every night from customers.  I think the issue lies in your view of what the job of the sales person really is, and what strategy best brings success to the sales person.
            A lot of sales people view themselves as merely extensions of the company’s customer service operations.  In other words, they believe that the reason their customers do business with them is because they (the sales person) bend over backwards to respond to every whim of the customer.  These sales people then inadvertently train their customers to call them with every problem and need they have.  Many times, many of these calls and problems could and should have been better directed to the company’s customer service representatives. 
            This is a common trap that sales people, particularly new sales people, fall into.  In an effort to fill up their days, to be seen as important to the customer, the sales person becomes the ultimate lap dog, dutifully chasing after every whim and responding to every request of the customer.  That creates a huge list of “things to do” for the sales person, which makes him/her very busy and feeling needed.
            However, it is a miserable and unwise way to define and go about your job.  The sales person should be seen as a professional consultant to the customer.  Someone who cares about the customer’s business, who creates and presents creative solutions to the customer’s deeper needs. 
            Questions and issues about back orders, invoice problems, delivery dates, pricing on routine orders, etc. are all more appropriately handled by an inside sales person or customer service representative. 
            A sales person does himself no good in the long term by attempting to handle every customer question or issue.  If you train the customer to call you for every possible issue, think about what message you are sending to the customer.  You are, in effect, say, “Sir, my company has no reliable people other than me.  We have no effective systems.  That’s why I have to handle every call.  Without me, the company would be worthless.”
As a buyer of goods and services, from my perspective, I wonder how substantial a vendor’s business is, and how good a vendor’s sales person is, if I can’t get my routine issues taken care of by a customer service representative.  If the sales person has to call back to handle every question, I really wonder about the value of that sales person and the reliability of that company.
            So, the real issue is how you define your job.  Are you a lapdog, responding to every whim of the customer, or are you a professional, capable and wiling to respond to the customer’s expressed needs?
            Once you resolve your definition of the job and how you want to position yourself, then the answer to the question above becomes clearer.  If you want to be the customer’s lap dog, then rejoice that you are getting seven or eight calls per night.  Gives you something to do, keeps you busy, and makes you feel important.
            However, if you view yourself as a professional, then you need to train your customers to take the routine issues to your customer service or inside sales group, and use the time with you for more substantial discussions of their needs and your solutions.

            Retrain your customers.  Give them your company’s 800 number and directions for what kinds of issues to take to the inside staff.  Stop answering your phone after 5 PM.  You deserve to have a life, too.  But you must train your customers to respect that.