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Re: cost of residential ISDN (fwd)

  ---------- Forwarded message ----------
  Date: Mon, 15 Jan 1996 18:10:43 -0600
  From: Marty Tennant <marty@sccoast.net>
  To: Multiple recipients of list <telecomreg@relay.doit.wisc.edu>
  Subject: Re: cost of residential ISDN
  I'm no central office salesman or engineer, but I used to sell PBX's for
  Southern Bell and AT&T.  I think most central offices sold these days that
  support ISDN are essentially or fully non-blocking, which means the
  switching matrix and communications bus can provide as many dialup
  connections, within the switch, as the number of lines supported.
  So that means that, within a 10,000 subscriber line capacity central office,
  5,000 folks could be talking to 5,000 other folks on the same switch at the
  same time.  No increase in costs would result (maybe more power consumption)
  and the capacity would be there from the time of installation.
  Does that mean that 4,000 folks could be talking to 4,000 other folks, and
  the remaining 2,000 subscribers calling out over interoffice trunks?  That
  would depend on the configuration of the switch and the number of
  interoffice and IXC carrier circuits provided.
  So that leaves you your variable costs, which are the interoffice, or trunk
  side connections.  These are mainly made over existing fiber optic links
  with incredible capacity and lowering costs, so that doesn't seem like such
  a big deal either.
  Seems to me that the real additional costs come from having to install
  special line cards to make the ISDN link work on the CO end.  This card
  would replace the analog interface card normally provided to a POTS
  subscriber.  Maybe the $4 a month increase you mention would be more than
  enough to cover the cost of the new line card.
  Perhaps an AT&T or RBOC techie could confirm this for us?
  Marty in MB