The Knights of Columbus, the world's largest Catholic fraternal service organization and a Fortune 1000 company, is headquartered in New Haven. Two more Fortune 1000 companies are based in Greater New Haven: the electrical equipment producers Hubbell, based in Orange, and Amphenol, based in Wallingford. Eight Courant 100 companies are based in Greater New Haven, with four headquartered in New Haven proper. New Haven-based companies traded on stock exchanges include NewAlliance Bank, the second largest bank in Connecticut and fourth-largest in New England (NYSE: NAL), Higher One Holdings (NYSE: ONE), a financial services firm United Illuminating, the electricity distributor for southern Connecticut (NYSE: UIL), Achillion Pharmaceuticals (NASDAQ: ACHN), Alexion Pharmaceuticals (NasdaqGS: ALXN), and Transpro Inc. (AMEX: TPR). Vion Pharmaceuticals is traded OTC (OTC BB: VIONQ.OB). Other notable companies based in the city include the Peter Paul Candy Manufacturing Company (the candy-making division of the Hershey Company), the American division of Assa Abloy (one of the world's leading manufacturers of locks), Yale University Press, and the Russell Trust Association (the business arm of the Skull and Bones Society). The Southern New England Telephone Company (SNET) began operations in the city as the District Telephone Company of New Haven in 1878; the company remains headquartered in New Haven as a subsidiary of AT&T Inc., now doing business as AT&T Connecticut, and provides telephone service for all but two municipalities in Connecticut.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): As one of the oldest telephone companies, the SNET started in what year?
1878