Location-based services and marketing require marketers and local service providers to have a fairly precise idea of where consumer mobile devices are located. There are two general types of location-based marketing techniques: geo-aware and geo-fencing. Geo-aware techniques identify the location of a user’s device and then target market- ing to the device, recommending actions within reach (which, in itself, requires the marketer to know where relevant things like stores are located). For instance, a mar- keter may target smartphones within several square city blocks to alert them to avail- able offers from participating merchants. Geo-fencing techniques identify a perimeter around a physical location, and then target ads to users within that perimeter, recom- mending actions possible within the fenced-in area. The perimeter can be from hun- dreds of feet (in urban areas) to several miles (in suburban locations). For instance, if users walk into the geo-fenced perimeter of a store, restaurant, or retail shop, they will receive ads from these businesses. Both of these techniques utilize the same locating technologies.