A new generation of ultra wide band (UWB) communication transceivers are becoming available that supports both positioning and communication tasks. Transceiver manufacturers envision that communication and positioning features are used separately and asymmetrically. We believe that this is an unnecessary restriction of the available hardware and that positioning and communication tasks can be active concurrently. This paper presents and investigates a medium access control (MAC) protocol which combines communication and positioning functions. The presented MAC protocol extends an established protocol concept which is used, for example, in the standard TinyOS low power listening component. Our experiments show that the existing data communication of a network can be exploited to gather position information efficiently.