A Location Server receives requests for subscribers that are within an Alert Area to enable notifications/alerts to be sent to the subscribers from an Alert Application. The Location Server extracts the location information by performing a search in a Database for subscribers that are located in the Alert Area. The quality of the locations in the database is dependent of the frequency with which a Core Network sends passive location data to the Location Server at network events when the Mobile Station is in contact with the network. The Location Server reconfigures the Core Network and Radio Access Network to send the information when it is needed. An advantage of the invention is that it is possible to provide services that require knowing which subscribers are currently located in a specific area in a flexible way without over loading the mobile network.