 and attractive according to the user's position. These messages are delivered to a person's mobile phone. The adver- tisement could, for example, show special offers in a department store that is close to the area where the mobile phone user currently is. C.3 LOCATION POSITIONING METHODS Positioning methods are based on three different types of technology: GPS-based, cell- coverage-based and triangular-based. CITARx and CI + RTT are coverage-based methods, while E-OTD and U-TDOA are examples of triangular-based methods. On the other hand, the technology behind positioning methods can be divided into three categories: network- based, mobile-phone-based and hybrid (a combination of network- and mobile-phone- based). In the following the basic methods for GSM and WCDMA networks are introduced. The GPS (Global Positioning System) method relies on a GPS receiver integrated to a mobile phone, SO this falls into the category of mobile-phone-based. The GPS method is accurate when finding the position of a mobile phone, but the downside is the mandatory GPS enabling feature in the MS. The device operability in GSM and WCDMA networks is determined by the mobile phone capabilities. The position of the mobile phone is estimated based on the measured distance between the GPS receiver and various satellites. The receiver needs to see a minimum of three satellites to be able to calculate a two-dimensional position. The more open is the view to the sky, i.e. the higher the number of satellites available, the better is the accuracy of the position estimate. The A-GPS (Assisted-GPS) is a hybrid method, where an integrated GPS receiver in a mobile phone handles the position calculation and the network provides assistance data. LMU units are needed in the network side to handle the delivery of the assistance data. With A-GPS it is possible to increase the performance of the GPS receiver. Firstly, with the assistance data, the GPS receiver is able to locate the satellites much faster; and secondly, the positioning accuracy is higher