Map service

The invention relates to a method at a wireless communications system which makes possible that map information can be generated in a service server and transmitted to a mobile client, where the map is gradually built up on a display unit depending on the client's geographical position and movement. A map over a whole district is transmitted in a data stream as separate, small map segments, but with only one call to the service server. The client unpacks the data stream in real time, extracts the map segments and shows them on the display unit as they are arriving. The map database sorts the map segments in a specific order, based on in which order the map segments shall be shown on the client's window. The sorting is based on: the client's position, the client's movement - both direction and speed, the time (RTT) for transmission of a map.