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re: satisfied customer
On Wed, 20 Mar 1996, W. Curtiss Priest wrote:
> I have appreciated the various responses to what we call
> digital vs. analog.
> The information about the digitization of inter-office voice
> connections was most informative.
> Nonetheless, I gather there is agreement that 28.8 Kbps modems
> are as "digital" as ISDN "modems."
> There was an argument that ISDN traffic moved by a digital network
> between COs while voice traveled by an analog route -- but given
> the statements that almost all inter-office voice is handled by
> the "digital network", this distinction, apparently, does not hold.
IN POTS, the signal voice or whatever travels by an analog line as an
analog signal to the Central office. When it reaches the switch is
encoded as a digital signal, and the switch then causes the signal to go
to the destination. that may be 3 inches away on another circut board,
or it may be over a long distnace circut.
at the "other end" the digital signal is decoded, and travels back allong
the copper wire as an analog signal.
If you are using modems, the modems convert your computers signals to
something that meets the limitations of the analog portion of the phone line.
With ISDN, your teliphone set converts your voice to a digital signal,
and so it is already digital when it reaches the switch. afterwards, it
again travels as digital all the way to the other phone. When used with
a computer, the computer data is just sent instead of the digital version
of your voice. NO MODEM, that is why the interface is not called a modem....
> So when we compare 28.8 to ISDN we really are talking about comparing an
> unconditioned local line with a conditioned local line with repeaters
> (if necessary). Once at the CO both data travel digitally.
NO. isdn travles in a totaly diferent format...it travels as a Pure
digital signal. POTS travels as plain old audio...
> Does anyone know if there are inherent advantages, efficiencies in
> using ISDN vis a vis a 28.8 modem where the connection is made
> at the CO?
Modem over phone line takes up a 56 k Channel at the cental office to
transport 28.8 K or less.
Charles MacDonald Stittsville Ontario firstname.lastname@example.org
A Ship in Port is SAFE, but that is not what a Ship is built for.