On Tuesday, July 8, 2014 12:48:43 PM UTC-4, Adam H. Kerman wrote:   
   > >SLC = Subscriber Line Concentrator   
   > I'm confused. What's the name of the device telephone companies used when   
   > they weren't installing sufficient numbers of local loops to meet a growing   
   > number of telephone subscribers, but bumped the frequency used within the   
   > loop so it could be shared by two different telephone subscribers?   
      
   I don't know the answer to your question.  But it should be noted that in the   
   1950s-60s there was a "1A concentrator" device which used switching techniques   
   to concentrate a large number of subscriber loops into a smaller number of   
   trunks to the central    
   office.  While the devices were supposedly well engineered to prevent   
   contention lockouts, apparently in practice they didn't give the best of   
   service.  Perhaps they were overused as it was a cheap way to save on building   
   more loop plant which was    
   expensive.   
      
   I can post additl info from the Bell Labs history, if desired.     
      
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