*BSD News Article 42911


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From: phr@netcom.com (Paul Rubin)
Subject: Re: flat rates for Internet/phone (Re: X on dial-in)
Message-ID: <phrD4JrEA.2ss@netcom.com>
Organization: NETCOM On-line Communication Services (408 261-4700 guest)
References: <D3s19v.4M7@pe1chl.ampr.org> <D4DH09.BAo@pe1chl.ampr.org> <phrD4G1np.MoG@netcom.com> <DANIEL.95Feb24172244@arcturus.compass-da.com>
Date: Sat, 25 Feb 1995 08:25:22 GMT
Lines: 52
Sender: phr@netcom19.netcom.com

In article <DANIEL.95Feb24172244@arcturus.compass-da.com>,
Daniel S. Barclay <daniel@compass-da.com> wrote:
>   Most parts of the US have flat rate monthly local service.
>   Lots of people use their phones all the time (such as for
>   24 hour a day SLIP connections) and their bills don't go up.
>   It really doesn't cost TPC any more to keep the connection up.
>
>Boy, is everyone so naive? :-) It does cost the phone company
>something - they can't used the resources (i.e., bandwidth) used to
>transmit your call to transmit someone else's call.  If everyone with
>flat-rate service tried to stay on the line 100% of the time, they
>probably couldn't work until the phone company installed more
>capacity, and (assuming their profit margins aren't excessive
>currently) the phone company would have to charge more to pay for it.

Lots of people are saying the same thing as you now, that
it costs TPC a lot more to service your line if you use it
all the time (always connected to the same local number, say)
than if you use it only a little bit.

But is that a documentable fact, or just speculation?  The main cost
of providing you with local phone service is the wire between the
switch and your house, and that wire is there whether you use it or
not.  Next comes some analog electronics to interface your phone to
the switch and provide ringing voltage, etc.  That too is there for
every phone, whether or not the phone is in use.  Next, I believe most
current switches are digital, so there are some codecs.  I don't know
if these are typically shared between a larger number of lines in
current switches (practice varies).  After that presumably there is
some kind of backplane that all the conversations are multiplexed
into.  Having more conversations active at once might increase the
bandwidth needs of this part, but inside-the-box is so cheap these
days that adding enough for one additional 24 hr/day phone call would
cost close to zero, I'd hope.

Does anyone know more about how this is done in big phone switches and
what the relevant costs are?  I'm hoping to see answers with *numbers*
or at least highly informed guesses (I can make uninformed guesses
myself without any assistance, thank you).

The voice/data switch that I program at work really would not cost any
more to operate if you used all the voice lines 24 hrs/day than if you
used them 5 minutes/day, just because its cost if you used it as a
pure phone switch (it's not intended for that but you could use it
that way) would be massively dominated by the phone line interfaces
and supporting hardware.  But all the phone lines you could throw at
it could not make a dent in the raw internal bandwidth available.
It's made to handle high speed data connections and phone calls on the
same wires, and the data traffic uses a lot more bits than the phone
stuff.