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            2000-04-25 
            
            
           
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            1996-01-02 
            
            
           
          Method and apparatus for alternate destination routing for switching egress customers 
        
         
        
          
            
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            1990-08-07 
            
            
           
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          System to pre-qualify copper subscriber loops for high bandwidth access service using subscriber or network generated tones 
        
         
        
          
            
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                (forum.php )
               
            
            
           
          
             
           
        
          
            
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                (en )
               
            
            
           
          
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          Pay telephone applique for subscriber carrier telephone system 
      
         
        
          
            
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            1976-02-03 
            
            
           
          PBX ground start trunk interface for station carrier systems 
        
         
        
          
            
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            1960-10-04 
            
            
           
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          電話交換システムにおける通話ルート指定方法 
        
         
        
          
            
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            1981-07-07 
            
            
           
          Coin signaling system 
        
         
        
          
            
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                (en )
               
            
            
           
          
            1975-02-11 
            
            
           
          Frequency division multiplex switching system 
        
         
        
          
            
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                (en )
               
            
            
           
          
            1940-09-03 
            
            
           
          Telephone system 
      
         
        
          
            
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            1996-07-17 
            
            
           
          Method of determining charges in telephone network 
      
         
        
          
            
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                (en )
               
            
            
           
          
            1954-03-23 
            
            
           
          Testing apparatus for carrier systems 
        
         
        
          
            
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            2005-09-09 
            
            
           
          중계회선 시스템에서 착신측 교환기로부터 전송되는비과금 안내를 구분하는 방법 및 이를 이용한 가상 번호통화연결음 서비스 방법