In 16 BIE (Before Internet Era), business purchases were made by decision-makers who needed to buy stuff for their operations, and they almost always needed help with technical questions, innovations, pricing, availability, delivery, etc.
That year, a/k/a, 1977, every business buyer went to work expecting salespeople to call on them, unscheduled. To a prospect, a “cold call” was not optimum, but usually was tolerated. Yes, in those days, you could walk into a business where you were previously unknown and leave with a sale. For current customers, dropping in was expected as good service. Remember, this was BIE, when a salesperson was the equivalent of a website.
As beautifully as this dance by motivated parties worked – one needed information and the other provided it – salespeople were still trained to conduct business with what Xerox (where I worked in 1977) called Professional Selling Skills (PSS). There were three key components to PSS: overcoming objections, closing skills and probing.