Content which is related to content being displayed on an out-of-home display screen is synchronized with being shown on an out-of-home display screen. A mobile device operates to receive content which is related to the content being displayed on the out-of-home display screen. The system operates based on mobile device location, out-of-home display screen location and the time of day. Based on the time and locations, a server can determine what content is on the display screen and can therefore serve related content based on that to the mobile device. It works passively with periodic regular updates of the mobile device location or actively through the use of a button (touch screen, keyboard, etc.) on the mobile device to signal the server to check its location and therefore identifying which display screen the mobile device is near.