A system comprising: at least one processor; and one or more computer-readable storage media including instructions stored thereon that, responsive to execution by the at least one processor, cause the system to perform operations including: receiving a request for a location of a client device; and identifying available location sources that are available to provide position information for the client device where each identified available location source is a different type of location source; characterized in that the operations include: selecting a combination of the available location sources based on pre-specified rankings of the respective location sources; generating an approximation zone (204, 206) using each selected location source based on respective received position information, the approximation zone representing a distinct geographical zone in which the client device is determined to be located using the respective location source; defining a target zone for the location of the device by utilizing an overlapping area of the approximation zones and excluding a non-overlapping area of the approximation zones from the combination of the selected available location sources; and determining a location of the client device using the target zone. at least one processor; and one or more computer-readable storage media including instructions stored thereon that, responsive to execution by the at least one processor, cause the system to perform operations including: receiving a request for a location of a client device; and identifying available location sources that are available to provide position information for the client device where each identified available location source is a different type of location source; characterized in that the operations include: selecting a combination of the available location sources based on pre-specified rankings of the respective location sources; generating an approximation zone (204, 206) using each selected location source based on respective received position information, the approximation zone representing a distinct geographical zone in which the client device is determined to be located using the respective location source; defining a target zone for the location of the device by utilizing an overlapping area of the approximation zones and excluding a non-overlapping area of the approximation zones from the combination of the selected available location sources; and determining a location of the client device using the target zone. receiving a request for a location of a client device; and identifying available location sources that are available to provide position information for the client device where each identified available location source is a different type of location source; characterized in that the operations include: selecting a combination of the available location sources based on pre-specified rankings of the respective location sources; generating an approximation zone (204, 206) using each selected location source based on respective received position information, the approximation zone representing a distinct geographical zone in which the client device is determined to be located using the respective location source; defining a target zone for the location of the device by utilizing an overlapping area of the approximation zones and excluding a non-overlapping area of the approximation zones from the combination of the selected available location sources; and determining a location of the client device using the target zone. selecting a combination of the available location sources based on pre-specified rankings of the respective location sources; generating an approximation zone (204, 206) using each selected location source based on respective received position information, the approximation zone representing a distinct geographical zone in which the client device is determined to be located using the respective location source; defining a target zone for the location of the device by utilizing an overlapping area of the approximation zones and excluding a non-overlapping area of the approximation zones from the combination of the selected available location sources; and determining a location of the client device using the target zone.