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Re: ISDN current events (fwd)
>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.