Re: ISDN current events (fwd)

[hes@unity.ncsu.edu]

  > ...
  >Uh, maybe what little I've read about ISDN has given me a misconception, but isn't
  >a D channel (Signalling Channel) *required*, in order to signal between the local
  >user and the switching equipment? Effectively, I thought the D channel was the
  >dialtone/touchtone portion of the connection, while a B channel would be the
  >talking/modem-data portion. Residential ISDN was supposed to be two 64K B
  >channels, and one 16K D channel. The D Channel doesn't talk to anything
  >but the phone company's switch, in order to request services. It can't be used
  >to transport customer data/voice to another remote customer. 
  
    This is correct - except that the D Channel can indeed be used to
  transmit data to/from other customers in addition to/from the telco.
  In fact when ISDN was first being touted, this was a "feature".  Since
  modems were usually 2400-9600 bps back then, this appeared to be a
  major upgrade in speed.
  
    Over the years modem speeds have increased to perhaps 14,400 -
  28,800 or so - and therefore using (most of) the D Channel's 16kbps
  for data no longer is attractive.
  > ...
  -- 
  --henry schaffer
  hes@ncsu.edu