The Transit Exchange
 
 The task of a transit exchange to transfer traffic between sub-ordinate exchanges
  in the network and to those further up in the network hierarchy. Figure 33 shows
  the position of the transit exchange in a multi exchange network.
 
 
Figure 33
 
  There may also be exchanges which only transfer traffic between the local
  exchanges, and which thus lack the ability to switch upwards in the hierarchy.
  Such an exchange is called a local transit exchange. Therefore in the transit
  exchange we do not need to have the stage . Also we do not need a functional
  block for charging. What remains is a system core consisting of the following
  functions.....

   Trunk and signaling stage
    Group switch
   Control
    Operation and maintenance

  The larger transit exchanges may have in addition an operator function for
  manual services. This may for example include.....

    Telephone monitoring when the subscriber's telephone is unmanned

    The 'centrax' service, where for example a firm can rent the function of a
      PABX and operator from the telephone administration

    Booked calls, i.e. to request for call set up between A and B at a given time

    Ordering dedicated (leased) lines e.g.. for data communication
 
 
 
 
 
 

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