The position of acting communications chief was bestowed upon an officer or another individual when the regular communications officer was unable to fulfill their duties.
In 3188, Michael Burnham offered the commission of acting communications chief to Federation liaison Aditya Sahil. In this position, he would continue the search for Burnham's ship, the USS Discovery. Sahil accepted the offer and affirmed it with a handshake. (DIS: "That Hope Is You, Part 1")