The present invention relates to Assisted Global Positioning System (AGPS) high accuracy positioning in unknown cell areas. By using an approach of three alternative steps a reference position, needed for AGPS positioning, is determined. The first step involves using the location of any neighboring cell. The second involves using the location of a cell within the same Location Area as the cell serving the portable communication device to position. The third step comprises determining a fixed point within the same geographical area as the Serving Mobile Location Center (SMLC) is serving, and using this fixed point as a reference location. Using the three-step approach the AGPS positioning can be optimized, providing a possibility to position, for instance a mobile phone, by AGPS even though the location of the cell serving the phone is unknown to the positioning node operating the serving cell.