Abstract: A positioning system which uses the Global Positioning System and a mobile communications network (PLMN), and a computer program for running the positioning system that uses the Global Positioning System and a mobile communications network (PLMN). It is a characteristic of the invention that a position data inquiry can be transmitted from a first mobile station (MS1), which is, for example, a combination of a GSM mobile communications station and a GPS receiver and which can determine positioning data using GPS via a mobile communications network (PLMN), advantageously using an SMS data transmission connection, to a second mobile station (MS2). When this inquiry is affirmatively answered in the second mobile station (MS2), the formation of and transmission of the position data to the first mobile station (MS1) via the mobile communications network (PLMN) is initiated. Lastly, the position of the second mobile station (MS2) is shown on the display of the first mobile station (MS1).