In the 1890s, telephone-based intercoms became popular after Kellogg created the first intercommunicating telephone system in 1894. The device connected two phones in different rooms, allowing the user to speak directly to the recipient without having to communicate with an operator. Hence apartment intercom systems for apartment entry systems were first used in the late 1950s.
With manufacturers embracing new technology, modern apartment video intercom systems are far improved than the primitive systems of the late nineteenth century. Tenants may now remotely open doors or converse with visitors via a one-way video link before giving them entrance.