Many techniques can be used by social engineers to gather information about their targets. When they gather information, then they can use it to communicate with the target or someone important to the success of the attack. Information can include a phone list, dates of birth, an organization's organizational chart, and so on.
Social Engineering: A Means To Violate A Computer System, p. 6 available at https://www.sans.org/reading-room/whitepapers/engineering/social-engineering-means-violate-computer-system-529, by Sans Institute (2007).
