The invocation of an intelligent network service in a call handler for calls being routed to mobile stations in a mobile communication network is done in such a way that if a call being handled is a call to be routed to a mobile station, and if it is determined that at least one intelligent network identifier is activated for that mobile station a further comparison of a stored condition parameter of the mobile station with a current value of that mobile station's condition parameter is performed, and where the decision regarding the invocation of an intelligent network service depends on the outcome of such a comparison.