Many companies spend time and money to gather data about the customer needs. They know the value of getting the customer needs and they understand that they have to do effort to get those needs whether by questionnaires or observation or focus group. However, less companies realize that they have to do similar effort to allow the each department to understand the capabilities, constraints and problems of other departments.

Following your example, if the sales person understand the developers capabilities….way of development…difficulties …he will not ask for impossible tasks.

We can take it from another perspective. Each department is a supplier to other department while the other department is the customer. So, we have to know our customer and supplier. It is the same as we know the company customer needs and supplier capabilities.