In the routing method and apparatus a second routing attempt via an alternate path from an originating node is implemented for a call given an unsuccessful routing attempt via a preferred route, i.e. the call is offered a further alternate path to the destination node. The evaluation of the effectiveness of the rerouting is updated at each call per traffic relationship (originating/destination node pair), using an evaluation storing device. A decision is made based on the evaluation as to whether the rerouting for this traffic relationship is to be maintained or throttled for following calls.