I was working with a client preparing the contents of a presentation that I would be delivering to their inside sales/customer service organization at their National Sales Summit. During our meeting, I made reference to calling on "prospects" and my client suggested that "I'm not sure you should use the term prospect with this group, because our inside people only work with existing customers in established relationships". The comment made me think and I asked "does that mean that you don't want them to cultivate new or add on business with your current customers?" Of course the response was "No, we need them to sell new items as well as increase sales with existing product lines".
I suggested that for that very reason we need to use the term "prospect" when talking with your sales team about their "customers". I went on to explain that too often in business/sales relationships sales people get comfortable with customers and come to "expect" the business. Rather than treating them like prospects, asking good questions and working to "earn" their business they can sometimes become to casual and give the customer the impression that they take them for granted.
I suggested that we should explain that every time we are trying to sell more of an existing product line or new products to a "customer", that we must understand that our customer has just become our "prospect". All customers become your prospects when they are buying more of what they currently buy or looking to buy a new product or item.
So, when the "prospect" asks if you have ________ and how much do you charge for it, resist the temptation to take the easy way out and answer the question. Instead, you might say "while I'm looking that up, is this a product you are currently using or something new that you were hoping would solve a problem?" You'll get more information that will ultimately help you serve your "customer" better.
Customer or prospect, you be the judge. Splitting hairs, maybe... but treat your customer like a prospect and they are much more likely to remain your customer!