Re: Macintosh echo
  By: mark lewis to Kurt Weiske on Mon Mar 06 2017 11:30 am

ML> "bit robbing" is/was used so the telco can carry more and
a lower quality 
ML> rate... in many cases, they swiped a bit from each connection... instead of
ML> 8 bits, you only got 7... 7 of those stolen bits made another connection
ML> that could be carried... they did similar with ISDN, too...

With ISDN in the US it was done to use inband SF signalling, which didn't make
a lot of sense since you had a whole D channel for call setup/teardown.
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