This paper presents the approach and the outcome of a study, called where's-the-phone to identify characteristics of how mobile phones are carried whilst users are out and about in public spaces. A series of contextual interviews were conducted in public spaces of Helsinki, Milan and New York collecting 419 responses in total. The results show a strong tendency by gender, with females using bags and males using trouser pockets to place their mobile phones. Comments from participants suggested users did not place the phone wherever available, but rather considered many aspects, such as the convenience, tolerance to multiple postures, risk of theft, comfort, or impact to their appearance. We learn that bag users miss incoming alerts more often than with other carrying methods. Based on the outcome of the study, we discuss the challenges in designing mobile devices, in particular mobile phones. (8 pages)