The essay delineates a multi-layered approach to a media history of mobile telecommunication. Whilst contemporary media such as the digital mobile phone are often seen as a recent “mobilization“ of media, the dual aim of the essay is to both historicize and theorize mobile communication media, focusing on their past and present configurations at the junction of media and mobility. Historically these configurations are discussed in regard to the early history of wireless, to the cell phone, and to Citizens' Band (CB) radio as well as to relations between mobilities of transportation and media within the history of telecommunication. Today's mobile media are thus traced back to a heterogenous historical landscape of mobile “media in transition“ (W. Uricchio). Theoretically mobile communication is discussed in its multiple and basically ambiguous mobility that shifts and broadens the notion of the “mobile.“ The term “ambulant,“ referring to something “not fixed,“ is used to mark this shift and is brought into play as a heuristical concept that allows us critically to rethink notions of mobility from a historical and media-related point of view.