This Recommendation contains the network dimensioning guidelines for circuit-switched networks using end-to-end GOS objectives. The dimensioning methods for networks with fixed traffic routing, time-dependent traffic routing, state- dependent trafñc routing and event-dependent traffic routing are described. The International Routing Plan envisages that international traffic relations may be served by any of the following routing arrangements: direct circuits;transit operation involving one or more transit centres for all connections,direct high-usage circuits with overflow via one or more transit centres.