Cooperative communication is a way of communicating that is much more likely to create the sense that the two people involved (let's say employee and angry customer) are working together -- on the same side.
The term was defined by Robert Bacal, some years ago, in conjunction with a group of online experts on communication and listening. The result was the book: Conflict Prevention In The Workplace - Using Cooperative Communication.
The principles apply to almost any situation, and the idea is about prevention. Many conflict occur as a result of subtle things people say -- an incorrect phrasing, or poor choice of words.
The opposite of cooperative communication is confrontational communication.