6.3.              501

,       
,   .      -
        ,
     TDM.    -
   ,      -
   TDM,     ,  -
     ,  - 
      .    V.90
      ,  
    .

        
  Switched 56 (  56 /)  
    ISDN (Intergrated Services Digital Network). 
Switched 56         -
   ,     1. 
    ,     -
 ISDN,    .

 ISDN      ,    -
,        ,     
    .     -
 ISDN    ,     -
          9600 /.
  ISDN     ,  -
   .      , -
 B-ISDN ( broadband  ),     
  (,   ),    -
   ,     .

      -
  ,    ,   -
    .

6.3.1.   

   

     , -
    .    
  POTS (Plain Old Telephone Service),  -   -
  , , ,  PSTN (Public Switched Telephone
Network)        -
.  ,       -
 .     9600 / 
 ,  ,     
     .   -
    56 /     , 
        ,   
        .