From: stephen@sprunk.org   
      
   On 08-Jul-14 15:07, hancock4@bbs.cpcn.com wrote:   
   > On Tuesday, July 8, 2014 3:10:51 PM UTC-4, Stephen Sprunk wrote:   
   >> Frequency multiplexing was analog "pair gain".  Systems were   
   >> available that supported up to eight POTS lines over a single pair   
   >> of wires.  At the other end, a matching device was used to turn   
   >> them back into analog POTS lines, which were connected to the   
   >> switch as any other.   
   >   
   > It would seem that with this arranagement, all eight users could use   
   > the pair simultaneously, since they were assigned different   
   > frequencies.   
      
   Yes.   
      
   > Would you know the specific code of this device and when it entered   
   > service?  It sounds like a great way to save on cabling since there   
   > is no blocking..   
      
   There were many types with varying capacities; Wikipedia has some   
   examples, but it's not a complete list.   
      
   > As menitoned, the older concentrator simply switched users around a   
   > smaller number of trunks with the potential of blocking.   
      
   Most other types of concentrators could be oversubscribed, though   
   whether the telco did so or not varied by the type of customers and how   
   much they were expected to use their lines--and how short of copper   
   trunk lines they were in the area.   
      
   Once the trunk lines went to fiber, mostly back in the 1990s, there was   
   no longer any need to oversubscribe.   
      
   S   
      
   --   
   Stephen Sprunk         "God does not play dice."  --Albert Einstein   
   CCIE #3723         "God is an inveterate gambler, and He throws the   
   K5SSS        dice at every possible opportunity." --Stephen Hawking   
      
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