Sirois has had a long career in corporate management. He is currently a director of the Canadian Imperial Bank of Commerce, Cossette Communication Group and Orchestre Symphonique de Montreal. He led BCE Mobile Communications from 1988 to 1990 as its chairman and CEO. Subsequently, he was chairman and CEO of Teleglobe, the leading provider of international long-distance and broadband services in Canada. He also served as chairman of Telesystem International Wireless, and founded and was chairman of Microcell Telecommunications, a GSM cellular provider in Canada best known for its Fido brand name. He was also a member of the G8 Dot Force, of the National Broadband Task Force, and was a founding member of the Washington-based Global Information Infrastructure Commission (GIIC).