A method is described for estimating longitudinal velocity of a vehicle on a road surface. The file is communicated to a file playback device such as a mobile receiver 28 from the storage device. Exposed contacts on the external surface provide an outside interface for add-ons. A punch member is located adjacent the pressing surface within the guidance housing. A number of said functional server nodes are provided to, in common, control at least a number of radio network control means such that said functional server nodes form a pool of functional server nodes, in which each functional server node is able to control any radio network control means.