Managed Network Systems Inc. (doing business as MNSi Telecom) is a Canadian Internet service provider (ISP) and phone provider located in Windsor, Ontario. Opened in 1995, it is the oldest ISP in the Windsor-London area, having started in September of that year as a provider of Dial-up Internet access. The company serves customers in the city, providing home and business phone, long distance, DSL Internet and fibre. MNSi also serves nearby areas of Southern Ontario, including Chatham, Leamington, LaSalle, Tecumseh, and Sarnia.