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Posted by on January 9, 2008, 10:18 pm
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Ah, the crystal clear quality of a Long Distance Telephone Call.
Though we might not be able to see the loved ones in person, at least
we will still be able hear their voices.
Not if your loved one has fallen in love with the plethora of cut rate
telecommunications. Nope. Garbled to the grave. Never thought it would
end like this. Can't even make sure if it's my mom on the line or
somebody else's.
***** Moderator's Note *****
The Bell Labs/Bellcore standard for voice circuits used to specify
response up to 4 KHz for toll circuits. That standard was enforced
throughout the Bell System, both in the design of toll equipment such
as L carrier and T carrier, and also in the design of intruments such
as the 500 set. The Bell System standard was, effectively, universal,
simply because the telephone business gernerated such huge profits
that managers weren't looking for economies. The public expectation
for telephone service remained unchanged until the breakup of the Bell
System.
There followed a race to the bottom in all aspects of service, not the
least of which was technical. Standards for voice circuit performance
were routinely ignored: basic tests such as echo-return-loss and
frequency response were ignored, often because the technicians weren't
trained to perform them.
That race slowed, but didn't stop, with several cycles of adoption and
rejection by decision-makers at all levels of American industry. After
several years of user complaints and some lawsuits, customer
perceptions had changed to the point that Sprint's "pin drop" campaign
was successful in positioning the carrier as a serious competitor to
AT&T and MCI.
It was, however, the widespread adoption of cellular service that
changed user's expectations forever. The change wasn't made for
business reasons, but for physical ones: with battery life of AMPS
phones severely limited, digital standards and instruments were
designed to maximize battery life at the expense of fidelity.
The resulting change in public expectations of telephone circuit
quality created a fertile ground for VoIP providers. Dropouts, echo,
and other artifacts of digitial radio systems, many of the
unavoidable, created lower expectations of fidelity on landline
circuits, and the rest is history.
Bill Horne
Temporary Moderator
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Posted by on January 10, 2008, 6:02 pm
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On Jan 9, 10:18=A0pm, jida...@jidanni.org wrote:
> ***** Moderator's Note *****
> The Bell Labs/Bellcore standard for voice circuits used to specify
> response up to 4 KHz for toll circuits. That standard was enforced
> throughout the Bell System, both in the design of toll equipment such
> as L carrier and T carrier, and also in the design of intruments such
> as the 500 set
The Bell System histories quietly point out that during WW II they
lowered the bandwidth to squeeze more channels on scarce toll lines.
I think it became 3 Hz or maybe 2.5 Hz. After the war there was such
a high demand for service they continued this for a while. How long I
don't know. This is one thing the Bell System didn't brag about. I
would imagine having a critical business conversation over long
distance during the war would not have been easy.
IMHO, a landline long distance call sounds better today than it did
say 20 years ago. While connections 20 years ago were quite good,
there was still some slight background noise and it made it clear you
were on a toll call. Today it sounds really good.
One limiting factor today is station equipment. A good corded phone
is superior to cordless phones. Further, many cordless users stray
too far from the base station or near interference and degrade the
signal. Seems like most residences use cordless phones today.
They came out with a replacement handset for the widespread 500 set
"G" model ("K"?) which does sound better. (My 20 year old Panasonic
phone has excellent sound quality.) But as long as a 500/2500 set is
in good condition it will offer very good sound. Even a 300 set with
"F" components sounds good (though admittedly the modules in my 302
set date from 1950, perhaps 1940 modules wouldn't sound as good.)
I've used pre-1938 phones (candlestick and 202 set) and they don't
sound very well. They function, you can get a message across, but not
all that great. Note that the "F" modules were retrofitted to sticks
and 202s.
> . The Bell System standard was, effectively, universal,
> simply because the telephone business gernerated such huge profits
> that managers weren't looking for economies. The public expectation
> for telephone service remained unchanged until the breakup of the Bell
> System.
The Bell System never generated huge "profits". It only made a modest
return on its investment. Be assured that over the years management
most certainly did look for economies. If a new product proved too
expensive to manufacture or service it was not offered. Manual was
converted to dial when, and only when, the economics of dial--in that
particular exchange--made dial preferable.
It wasn't until well after WW II that the idea of universal service
for all truly took hold. The Bell System sought universal service and
low prices, but there was a limit to how low they were willing to go.
Before say 1955, telephone service, even message rate 4-party line,
was simply too expensive for many people to afford. By 1955 wages had
climbed enough and telephone rates stabilized that the vast majority
of people could afford a phone. Long Distance was a luxury only for
the wealthy until about 1963 for similar reasons. People made do with
letters. Until about 1971 long distance was still something most
people used sparingly at home. Around 1971 they introduced late night
DDD discounts.
The big difference was that the first priority was service, not
profits. Engineering, not marketing, was the focal point.
After divesture marketing became supreme, engineering secondary.
> It was, however, the widespread adoption of cellular service that
> changed user's expectations forever. The change wasn't made for
> business reasons, but for physical ones: with battery life of AMPS
> phones severely limited, digital standards and instruments were
> designed to maximize battery life at the expense of fidelity.
Ironically, today I used my cell phone for a personal business call.
There was nasty echo on the line and I had trouble dealing with the
other person. My prior analog phone had much better quality. My cell
phone is a nice convenience, but I don't like it very much. If they
weren't pulling the plug on analog, I'd still use that.
I don't understand how swarms of people just have their cell phone
_literally_ attached to their ears. I don't like the idea of talking
in public where outside noise is a distraction and others can hear
your conversation. I miss the old oak phone booths with the little
chair and table, light and fan.
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Posted by T on January 11, 2008, 12:42 pm
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@f10g2000hsf.googlegroups.com>, hancock4@bbs.cpcn.com says...
> On Jan 9, 10:18=A0pm, jida...@jidanni.org wrote:
> > ***** Moderator's Note *****
> > The Bell Labs/Bellcore standard for voice circuits used to specify
> > response up to 4 KHz for toll circuits. That standard was enforced
> > throughout the Bell System, both in the design of toll equipment such
> > as L carrier and T carrier, and also in the design of intruments such
> > as the 500 set
>=20
> The Bell System histories quietly point out that during WW II they
> lowered the bandwidth to squeeze more channels on scarce toll lines.
> I think it became 3 Hz or maybe 2.5 Hz. After the war there was such
> a high demand for service they continued this for a while. How long I
> don't know. This is one thing the Bell System didn't brag about. I
> would imagine having a critical business conversation over long
> distance during the war would not have been easy.
>=20
> IMHO, a landline long distance call sounds better today than it did
> say 20 years ago. While connections 20 years ago were quite good,
> there was still some slight background noise and it made it clear you
> were on a toll call. Today it sounds really good.
>=20
> One limiting factor today is station equipment. A good corded phone
> is superior to cordless phones. Further, many cordless users stray
> too far from the base station or near interference and degrade the
> signal. Seems like most residences use cordless phones today.
I found that to be the case with old 900MHz and 5.8GHz phones. But these=20
DECT cordless phones I have now are rock solid. They operate around the=20
1.9GHz range.
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Posted by Bill Horne on January 11, 2008, 10:15 pm
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>
> IMHO, a landline long distance call sounds better today than it did
> say 20 years ago. While connections 20 years ago were quite good,
> there was still some slight background noise and it made it clear you
> were on a toll call. Today it sounds really good.
The "slight background noise" was artificially produced, and injected
into the calls for precisely the reason you cite: it was added to the
call to make it clear you were talking on a long-distance circuit.
Bell Labs engineers had to add a "noise" generator to the L carrier
design because customers were so used to background noise on earlier
carrier circuits that they assumed a lack of background sound meant the
call had been disconnected, and they would hang up without reason.
Bill Horne
--
Bill Horne
Temporary Moderator
Telecom Digest
(When sending a post to the digest, please put "[Telecom]"
{without the quotes but _with_ the brackets} in your subject
line, or I may never see your mail. Thanks!)
(Remove QRM from my address for direct replies.)
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Posted by Rob Levandowski on January 12, 2008, 10:25 am
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> The "slight background noise" was artificially produced, and injected
> into the calls for precisely the reason you cite: it was added to the
> call to make it clear you were talking on a long-distance circuit.
>
> Bell Labs engineers had to add a "noise" generator to the L carrier
> design because customers were so used to background noise on earlier
> carrier circuits that they assumed a lack of background sound meant the
> call had been disconnected, and they would hang up without reason.
That's true today with VoIP systems. For example, Cisco's VoIP system
has an option to add "comfort noise" to calls. The noise is generated
by the telephone, not the network; most VoIP systems detect (relative)
silence and compress it down to a "no sound" flag. The phone on the far
end either makes no noise (and thus sounds, to people used to analog
telephones, like the call has been disconnected), or generates "comfort
noise" to simulate the slight hiss of a POTS line in good repair.
There is such a thing as "too clean," I guess...
--
Rob Levandowski robl@macwhiz.com
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