This means "Director of Sales." It is the title of a position in the hotel industry (and other industries that involve selling to customers). Cold calling is a sale method, and this article is suggesting that hotels not use it.
The general idea that is being conveyed is that there are some people who have a boss that wants to see hours logged, rather than successful outcomes. In that situation, an employee may use cold calling as a way to pass the time, just to show the management that he is attempting to get new customers.
If he spent less time doing more effective things, his management still would want more because they are focused on the hours, not the results.