Bell System Practices 636A - CONNECTIONS; 2.06 Supplementary Hold Details; 2.07 Key Position Conversion; 2.08 Ringer;Line Cutoff Key Usage

 
       
  
     
        
        
     
  
       
       
      
    
     
    

      
    

      
 
    

       
       
           
   
 
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     
   
   

     
   

    