ion and calling/moving interest. The end-to-end traffic matrix (Table 4.3) shows the distribution of calls to other switching sites in the network. Calling interest is the probability of a call terminating in a given switching site. This probability reduces with distance in an exponential way. Moving interest models the moving behaviour of subscribers in a given network. The probability that a subscriber temporarily relocates to a new location further from their home location reduces exponentially with distance. Other factors affecting the traffic matrix include subscriber distribution. Traffic moving to a given switching site will be directly proportional to the amount of subscribers in that location of the network. Routing Plan The routing plan would define the routing strategy for internal calls, external calls and international calls. It is also important to note the routing strategy for other types of calls, i.e. PABX (private automatic banch exchange), calls centre, service numbers, other services, etc. The routing strategy depends on the switching network structure, that is: the interconnect plan, i.e. switching connections by direct link, and which connections are made indirectly via transit switches; the number and locations of transit switches; the number of switching gateways to other networks; the number of levels of transit switches used; re-routing mechanisms for the congestion and failure situation, e.g. alternative routing, load sharing, dynamic routing, etc. As a basic rule, a direct interconnect is provided between two switching sites if there is intense traffic between the two exchanges. Should the amount of traffic be low, however, it is preferable to use existing interconnect and exchanges as a transit to reduce transmission costs. The decision of how to connect Network Design Process Table 4.3 End-to-end traffic matrix Network total interswitch traffic Total 10 232 10 232 116.7 116.7 116.7 116.7 116.7 116.7 116.7 116.7 Outgoing traffic Total 10 232 10 086 Incoming traffic Total Measured inte