Mobile phones are increasingly becoming ubiquitous computational devices that are almost always available, individually adaptable, and nearly universally connectable (using both wide area and short range communication capabilities). Until Star Trek -like speech interfaces are fully developed, mobile phones seem thus poised to become our main devices for interacting with intelligent spaces and smart appliances, such as buying train passes, operating vending machines, or controlling smart homes

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... .g., TVs, stereos, and dishwashers, as well as heating and light). But how much can a mobile phone simplify our everyday interactions, before it itself becomes a usability burden? What are the capabilities and limitations of using mobile phones to control smart appliances, i.e., operating things like ATMs or coffee makers that typically do not benefit from remote control? This paper presents a user study investigating the use of a prototypical, mobile phone based interaction system to operate a range of appliances in a number of different task settings. Our results show that mobile devices can greatly simplify appliance operation in exceptional situations, but that the idea of a universal interaction device is less suited for general, everyday appliance control.