Other Types of Exchange
 
   The local exchange we looked at earlier had the tasks of switching calls between
   its own subscribers, and of transfer upwards in the hierarchy for the long
   distance calls. The task common to all exchanges at the level between local
   and international exchanges is that of transferring traffic between the exchanges
   in the network.

   This task is often combined with serving its own subscriber area. At the top of
   the hierarchy, in the international exchange, the main task is switch international
   traffic. Network hierarchy is shown in Figure 32 .

 
 Figure 32
 
   There are four principally different types of exchange.......

    1.  Exchanges for local traffic
    2.  Exchanges or both local and transit traffic
    3.  Exchanges for transit traffic
    4.  Exchanges for international traffic
 
 
 
 
 
 

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