telecom@ucbvax.ARPA (08/13/85)
From: Moderator <Telecom-REQUEST@MIT-XX.ARPA>
TELECOM Digest Monday, August 12, 1985 3:16PM
Volume 5, Issue 16
Today's Topics:
(700) 555-4141
Re: TELECOM Digest V5 #15 - 800 numbers
Some information, and request for more, on Telstar.
TELECOM Digest V5 #15
looking for old old phone
800 numbers & Shannon theory
volume 5 issue 14
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Date: 9 Aug 85 18:49:00 EDT
From: " David Flory" <shadow@ru-aim>
Subject: (700) 555-4141
About the widespreadness of knowledge on the existance of (700) 555-4141,
t
the only place I ever saw anything on this was in some newsletter sent out
to ITT long distance customers about a year ago.
Shadow
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From: ima!johnl@bbncca
Date: Sat Aug 10 19:26:00 1985
Subject: Re: TELECOM Digest V5 #15 - 800 numbers
It is my understanding that inter-lata 800 service will be provided solely
by AT&T for quite a while yet. The problem is that unlike all other kinds
of calls, the carrier is selected by the recipient of the call rather than
the originator. Until the whole country is upgraded to CCIS (and I think
also to equal access) the phone network isn't smart enough to query an
800 translation data base and then select the carrier. In my exchange, at
least, the exchange will not complete an 800 call if you dial a 10xxx
prefix first -- it's considered to be like an intra-lata call in that my
local phone company decides how to route it.
In the meantime, though, lots of the other long distance companies have
800-like service. For example SBS lets you set up automatic collect
numbers so you dial 950-1088 + some short code and SBS places the call to
you and charges you their regular rate. The disadvantage of this
is that it's hard to explain to the telephone using public how to make such
a call and to assure them that it really is free. Handy for outfits with
travelling salesmen, though.
John Levine, Levine@YALE.ARPA
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Date: Sat, 10 Aug 85 19:37:48 cdt
From: hplabs!csu-cs!isucs1!shaver@Berkeley (Dave Shaver)
Subject: Some information, and request for more, on Telstar.
Sometime ago there was BRIEF mention of the "Telstar" telephone control
system. Basicly I would like additional info on this product. Is anyone
else selling them besides Jameco Electronics? [In Belmont, CA] Did the
project get scrapped, and then did Jameco picked up the stock? Is this really a
good machine, and what can I expect out of it? Is $99.95 a good price
for the unit? [Cheaper anywhere else?] Below is a copy of the information
that is present on the cover of Jameco's Spring 1985 flyer. [#127] I
have no contact with Jameco, or Western Electric Company which is claimed
to manufacture the device as per Jameco. Any info outside of what's below,
or the answers to the my questions can be mailed to me. I will summarize,
and post if interest warrants it. [If not, I will mail copies of the
summation to those requesting it.] My use for the Telstar system is for
home/personal use. I would like an answering machine function of sorts.
I don't have any info outside of what's below.
/---=[
// Dave Shaver
<< UUCP: {okstate|umn-cs|csu-cs}!isucs1!shaver CSNET: shaver@iowa-state
\\ [Iowa State University - Ames, IA] These are my comments, no one else's.
\---=[
[=--=]
This info included for the benefit of those interested, and that have not seen
Jameco's Flyer. I have added comments in square brackets [like this] for
some of my additional questions.
[From the cover of Jameco's Spring Flyer {#127}]
Telstar (tm)
The call control system for you business or personal needs.
Your programmable, 24 hour a day telephone control system is here!
o Stores 30 calls for you. Its friendly voice tells caller to leave their
number, which is stored in Telstar's memory. When you check in for
messages, its voice reports the numbers that called, and time of call.
[Does this means that the machine answers the line with a pre-canned message,
and accepts Touch-Tone digits, then saves them for later retrieval?]
o Easy to program. Voice prompts provide step by step programming
instructions.
o Remote access. Call your Telstar call control system from any Touch-Tone
phone anywhere to receive messages and to use other features.
[These "messages" I would guess are the numbers gathered above from remote
callers. Does this unit have any form of a "standard" answering machine,
or some comparable system? {standard: Answer the line with a taped message,
then start another tape and record the remote callers message.}]
o Voice synthesis. Talks to you and callers via friendly, life-like voice
synthesis. It's clear, easy to understand.
[I have heard other "life-like voice synthesis" that's "clear and easy to
understand." Is this a "good" synthesis? Understandable over long distance
lines?]
o Call Screening. Identify calls you want to receive. System will announce
only those calls you want to receive, and record all others.
[Can this option be turned on and off? How many identifying numbers are
allowed?]
o Call forward announcement. Lets you tell your callers where you can be
reached. You can change the announcement as often as needed, even remotely.
[Is this option switchable with just the standard "record" option that excepts
remote users numbers? {or however that works}]
o Last number dialed. Conveniently remembers last number dialed, especially
helpful when they are busy or unanswered.
o Security controlled access. Through the use of a special code you prevent
unauthorized access to the system.
[What's the length of this "security" code, and how is it used? Do you call
up the Telstar system, and when it asks for your number, enther the code?]
o 50 name directory for convenient dialing. You can store 50 numbers and
reach them easily by just dialing their names on your touch-Tone telephone
keypad.
o Built-in calendar. Automatically logs the time and date of incoming calls.
Tells you the time and date via voice synthesis.
o 2 button emergency calling. Telstar provides fast, reliable two-button
dialing of medical, police, and fire numbers.
o Many other features. There are additional conveniences that come with
having Telstar, such as Intercom, Hold, Long Distance Restriction, and more.
[Any comments on any of these features?]
o Brand new in factory cartons.
[Please note: TELECOM is not to be used as an advertising medium. Any
blatantly commercial messages will not be posted to this list. --JSol]
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Date: Sun, 11 Aug 85 14:38:12 EDT
From: "Marvin A. Sirbu, Jr." <SIRBU@MIT-MC.ARPA>
Subject: TELECOM Digest V5 #15
Regarding the upper limit of bit rate over a voice grade line:
Some 37 years ago Claude Shannon, then of Bell Labs, developed his
famous theorem which showed that any communications channel has
an upper limit as the bits per second that can be shoved through it with
a tolerably low error rate. The Capacity C is given by
C = BW*log (1 + S/N)
where BW is the bandwidth (nominally 3.3 KHz for a voice line) and
S/N is the average signal to noise ratio.
Since the signal power you can shove over a phone line is limited by
both regulation and telco equipment, and the average noise level is well
known, and a function of the kind of technology typically used for telco
transmission lines, the capacity can be calculated. I believe it works
out to about 35 kbps.
For more information see the article by Gallagher, Forney, et al in the
March 1984 issue of IEEE Selected Areas in Communications.
------------------------------
Subject: looking for old old phone
Date: 11 Aug 85 21:27:59 EDT (Sun)
From: cspencer@BBNCC5.ARPA
I'm looking for a circa 1920 candlestick style phone.
I'd like a real one, not a repro. Can anyone give me any
pointers? Is there a standard selling price for these things?
I just saw one going for $250...ahem.
-cliff
{bbncca,bbnccv}!cspencer
cspencer@bbncc5
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Date: Monday, 12 Aug 1985 05:56:54-PDT
From: goldstein%donjon.DEC@decwrl.ARPA (Fred R. Goldstein)
Subject: 800 numbers & Shannon theory
Re: Telecom V5I15's question about 800 numbers; MCI does NOT offer 800
service, nor do any carriers other than AT&T. This is a sore point
about the divestiture terms; AT&T kept the ownership of the 800 number
data base, which translates all 800 numbers to underlying public network
numbers based upon originating area code, time of day, etc. The Bell
operating companies are beginning to build their own data bases, and
expect to have them by 1986, at which point the ownership of "area code
800" will be snarfed away from AT&T and given to Bellcore or someone like
that. THEN and only then will the snit carriers get access.
There is an alternate proposal to declare certain NXX codes in the 800
series to be property of certain carriers; i.e., 800-mci-XXXX numbers
all go to MCI (where mci is something or other). But nobody really
likes this plan, so it will probably not go ahead. For one thing,
it makes alpha numbers (like 800-LIBRARY) impossible.
Re: 10xxx codes; these were originally 10xx codes, but some resellers
complained that they wouldn't fit, so the list was expanded to permit
a thousand codes. They are national in scope, so you don't need to know
the code for your favorite snit in every city. I don't think more than
a couple dozen are really in use, though.
Does anyone know if it is "normal" to have to dial 10xxx-1-etc. to make
a call via "equal access"? I thought 10xxx by itself would do, but
I get a recording "you must dial 1" if I don't dial a second one. Seems
redundant. (This is in Brighton, MA.)
Re: How fast can modems get? Some years ago, Claude Shannon, then of
Bell Labs, developed a branch of information theory that covers this
question. My recollection, not knowing the formulae, is that a so-called
voice-grade line (3 kHz bandwidth, 20 dB snr) has a theoretical limit
of 26 kbps. Today's 16 kbps modems are coming close. If you increase
the bandwidth or signal to noise ratio, the maximum data rate rises
proportionately. Don't expect 50 kbps on a voice line, but 56 kbps
ISDN-style switched service is said to be on the way (but not deployed
widely until the next decade, at least in this country).
------------------------------
Date: Mon 12 Aug 85 15:03:20-EDT
From: Jon Solomon <JSOL@MIT-XX.ARPA>
Subject: volume 5 issue 14
Apparently some of you have not received issue 14. Issue 14 does
exist (no, I haven't skipped a number ... this time...)
If you haven't received it, please send a note to telecom-request
and I will remail it to you. If enough of you reply, I will resend
it to everyone. Apparently issue 14 never made it to USENET either.
Cheers,
-yfntm (your friendly neighborhood TELECOM maintainer).
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End of TELECOM Digest
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