This study examined the relationship between sustainability of mobile phone users and work-life balance. Twenty-seven interviews were performed on managerial level mobile phone owners over the duration of a month and half. The study extends Clark's [1] original Border theory that fails to mention how mobile phones (or indeed any other information and communication technology) influence the borders between the two domains. This study found technology has a definitive impact with separate users groups emerging from the data; border-extenders, border-adapters and border-enforcers.