ormance issues. To be able to increase network performance during the optimisation phase, it is important to investigate any problematic areas and locations in the network. However, the network management system (NMS) is able to provide network performance statistics with best accuracy of the cell level. This does not describe the actual position of interest, for example a location where a dropped call has happened. Location positioning methods enable higher accuracy to investigate geographically the problems in call events. Also, the geographical distribution of mobile phone users itself is interesting and useful information, especially when launching new services. The commercial services can be targeted either to private users or to companies. Examples are information services, navigation, tracking and advertising. Location-based information services provide for users desired information based on lo- cation. For example, yellow pages, news and traffic information can be delivered to the customer. The information delivery can be an instant answer to a query, such as "where is the nearest hotel?" Some information can be delivered repeatedly according to an agreement with the service provider and the customer, for example a weather forecast every morning. With the location-based navigation services the type of information is similar, but the main issue is the navigation instructions. The information given is how to travel from the current location to a chosen point. Location-based tracking can be directed to a person or a valuable object, to trace its move- ments. When considering a person to be traced, this service can be used in the same way as the safety telephone system, though the service is wireless. Tracking provides help for the relatives of a person who needs continuous support, such as an aged person or a child who needs medication. Tracking can be used, for example, by a car leasing company to trace its vehicles. LOCATION POSITIONING METHODS Location-based advertising delivers messages that are relevant