This thesis is an after sales study for Ericsson Mobile Communication Inc. using the tool simulation. The study is built up by these different strategic simulation models. The global model is dealing with the total after sales flows generated globally. The business area model is dealing with the after sales flows and the associated costs in business area, Asia Pacific. The model Asia Pacific is a temptation to implement costs variables in to strategic simulations. Finally, the Country model deals with the after sales in certain selected countries in which the after sales volumes are article and action needs to be taken. This thesis is a tool for Ericssons After Sales organization in their decision for how they should organize their future activities. The software package for the simulation is WITNESS ver. 6.0. The result obtained by the simulation is foremost an identification when and where Ericsson Mobile Communication Inc. has to invest in new repair capacity.