From: stephen@sprunk.org   
      
   On 30-Jun-14 16:05, hancock4@bbs.cpcn.com wrote:   
   > On Saturday, June 28, 2014 3:10:36 PM UTC-4, Stephen Sprunk wrote:   
   >   
   >> Analog multi-line phones mean you need a wire pair for every line   
   >> that appears on the phone--and that's expensive after the 3rd line.   
   >> Digital phones can have lots of lines, limited only by the number   
   >> of buttons on the phone.. But more buttons still costs more money;   
   >> in most cases, the typical desk phone only has 2-3 line buttons,   
   >> and only a receptionist's phone has more (one for every user's   
   >> extension).   
   >   
   > I'll have to double check the technology, but I'm pretty sure the   
   > 'electronic' key system telephones introduced by the Bell System   
   > circa 1980 (the "Horizon" system and later "Merlin" ?) did not   
   > require a wire pair for each line--the electronics allowed one pair   
   > for voice and maybe one pair for signalling.  Everything else was   
   > analog.  These phones also introduced the use of LEDs instead of   
   > incandescent lights for signal purposes.   
      
   I think we established elsewhere in the thread that those were what are   
   now called "digital" phones.   
      
   The digital signaling, in effect, reconnects the single analog pair to   
   various lines, so you only need the one.  That was when multi-line PBX   
   phones really became mainstream.   
      
   >> TRE's trains have real bells; they ring whenever the ditch lights   
   >> are set to flashing, i.e. every grade crossing and when entering or   
   >> exiting a station. It's even more annoying than the (very loud)   
   >> horn.   
   >   
   > The NJT River Line bells are controlled by the operator and usually   
   > sounded briefly.  It seems on most RR trains the ditch lights flash   
   > if the whistle is used, not the other way around.   
      
   TRE's trains have a switch to set the ditch lights to flashing; it's not   
   connected to the horn/whistle.   
      
   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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