ISDN Centrex System

[CURTIS WENSLEY <WENSLEYC@EXCELINC.COM>]

  I have not heard much about ISDN Centrex System.  I have been
  checking into ISDN and a local ISP has setup this Centrex System. 
  As far as I understand, I do not have to pay any usage fees
  because I do not have to dial outside this system.  It's like I am
  using the phone system within a company so I never have to dial a
  outside line.  The ISP then forwards the charges to me as a flat
  rate.  It sounds to me that every ISP should go this route.  A lot
  more people would be jumping abord.  As far as I can tell, there
  would be a inital cost to have the line run from your ISP, but
  after that the monthly cost is minimal.