Old Technology Museum Exhibit
hanc...@bbs.cpcn.com
cranked phonographs, candle stick phones, etc.
For full article please see: http://www.nytimes.com/2010/01/03/nyregion/03artsli.html
Morten Reistad
SO?
I have an _operational_ 1892 Ericsson candlestick phone; connected
to a Xorcom XR0003. I have to generate the calls from a web page,
though. The 1938 EB phone can dial, but I have to hack the pulse
cadence; Z cadence was not it the standard VoIP libraries.
Sound levels are pretty weak, though.
But telecom support for legacy systems can span a century.
Yes, I have a phonograph as well. The music industry still stick
to that business model.
-- mrr
hanc...@bbs.cpcn.com
> I have an _operational_ 1892 Ericsson candlestick phone; connected
> to a Xorcom XR0003. I have to generate the calls from a web page,
> though. The 1938 EB phone can dial, but I have to hack the pulse
> cadence; Z cadence was not it the standard VoIP libraries.
My 1938 phone plugs directly into the phone line and works fine as a
dial phone at work or at home. No intermediate interface required.
The sound quality is slightly less than a modern phone but certain
adequate enough. The only weakness is calling a business that
requires Touch Tone to work their menus. Many places these days do
not allow a caller to simply wait for a human to answer; one MUST
enter something.
My 1928 phone + ringer box also plugs directly into a phone line and
works. However, the sound quality is poor.
Morten Reistad
<hanc...@bbs.cpcn.com> wrote:
>On Jan 5, 3:21�pm, Morten Reistad <fi...@last.name> wrote:
>
>> I have an _operational_ 1892 Ericsson candlestick phone; connected
>> to a Xorcom XR0003. I have to generate the calls from a web page,
>> though. The 1938 EB phone can dial, but I have to hack the pulse
>> cadence; Z cadence was not it the standard VoIP libraries.
>
>My 1938 phone plugs directly into the phone line and works fine as a
>dial phone at work or at home. No intermediate interface required.
>The sound quality is slightly less than a modern phone but certain
>adequate enough. The only weakness is calling a business that
>requires Touch Tone to work their menus. Many places these days do
>not allow a caller to simply wait for a human to answer; one MUST
>enter something.
The only thing the 1938 phone has different is that the pulse
cadence is Z; unique to Oslo and New Zealand, so the switch has
to do a "tr '0123456789' 1234567890'"; or I will have to paste
new digits on the phone. It also has a somewhat low volume, so
a +5dB adjustment on the line is a welcome switch feature.
>My 1928 phone + ringer box also plugs directly into a phone line and
>works. However, the sound quality is poor.
The 1892 one has some carbon clicking, the carbon in the microphone
would benefit from being changed. And the output levels are really
low; it needs a bigger boost. But it is still audible and I can complete
a useful phone call on it.
This is 118 years worth of direct, backwards compatibility with
a working system. How many other businesses do this as a matter of
course for regular production systems?
OK, pre-1890 railroad cars work, but steam engines are not
allowed as propulsion on standard track anymore because of the
fire hazard.
Pre-1900 cars cannot even run on standard gasoline. (They usually
run on seventy-something octane, which you can mix from 70% gasoline
and 30% kerosene).
The current 50Hz 220V electricity standards date from late 1890s,
but was in a minority until around 1920.
1892 is 4 major building-code revisions ago. Anything before 1936
must be significantly refurbished if you touch the building at all.
This also applies to phone wiring. But 1937 phone wiring is probably
cat3 compliant, and can be used as-is.
-- mrr
Charles Richmond
You can create a little "jig" to produce the tones and then beep
them directly into the phone receiver. The other downside is that
it takes *much* more current to ring the bell on your 1938 phone
than to ring the modern phones, and that power comes directly off
the phone line. ISTM that the phone company allows you *two*
"ringer equivalencies" on your single number line, a "ringer
equivalency" being the current it takes to ring a real bell in a
telephone.
But I think I get your point: it's amazing to be able to use such
an old device on the modern phone network!!!
--
+----------------------------------------+
| Charles and Francis Richmond |
| |
| plano dot net at aquaporin4 dot com |
+----------------------------------------+
D.J.
wrote:
>1892 is 4 major building-code revisions ago. Anything before 1936
>must be significantly refurbished if you touch the building at all.
>This also applies to phone wiring. But 1937 phone wiring is probably
>cat3 compliant, and can be used as-is.
Something similar happened in Hurricane Katrina hit areas. The water,
electricity, and sewage lines had to be brought up to recent
standards. Before the storm hit many of those same lines were
pre-1950. They no longer met code requirements. The cities and towns
were not allowed to renistall the lines near the beach unless they
were brought up to the msot recent standards. Much more costly, but
safer in the long run.
JimP.
--
Brushing aside the thorns so I can see the stars.
http://www.linuxgazette.net/ Linux Gazette
http://www.drivein-jim.net/ Drive-In movie theaters
http://crestar.drivein-jim.net/ Jan 9, 2010
hanc...@bbs.cpcn.com
> The other downside is that
> it takes *much* more current to ring the bell on your 1938 phone
> than to ring the modern phones, and that power comes directly off
> the phone line. ISTM that the phone company allows you *two*
> "ringer equivalencies" on your single number line, a "ringer
> equivalency" being the current it takes to ring a real bell in a
> telephone.
The phone line can support much more than two ringers, more like four
or five unless one lives far from the C.O.
ArarghMai...@not.at.arargh.com
IIRC, back in the old days, if you had more than 2 or 3 phones, the
installer opened the phones and did something to the ringer. I think
he would adjust the tension on the ringer so that it needed less
current to work properly.
This would be for ordinary 500 & 2500 series phones - ringer
equivalence 1.0A types.
--
ArarghMail001 at [drop the 'http://www.' from ->] http://www.arargh.com
BCET Basic Compiler Page: http://www.arargh.com/basic/index.html
To reply by email, remove the extra stuff from the reply address.
Dav Vandenbroucke
wrote:
>The cities and towns
>were not allowed to renistall the lines near the beach unless they
>were brought up to the most recent standards.
One wonders if they could have found contractors that could have done
otherwise.
Dav Vandenbroucke
davanden at cox dot net
D.J.
<dav_and_france...@compuserve.com> wrote:
>On Sun, 17 Jan 2010 19:38:23 -0600, D.J. <jollyc...@cableone.net>
>wrote:
>
>>The cities and towns
>>were not allowed to renistall the lines near the beach unless they
>>were brought up to the most recent standards.
>
>One wonders if they could have found contractors that could have done
>otherwise.
The Feds said bring it up to code or don't reinstall.
hanc...@bbs.cpcn.com
> IIRC, back in the old days, if you had more than 2 or 3 phones, the
> installer opened the phones and did something to the ringer. I think
> he would adjust the tension on the ringer so that it needed less
> current to work properly.
> This would be for ordinary 500 & 2500 series phones - ringer
> equivalence 1.0A types.
I've never heard of that practice. Note that on 500/2500 phones the
subscriber adjusts the bell themselves to control loudness.
It was extremely common for a household to have three extension phones
it (upstairs, first floor, basement). A large home could easily have
four. The telephone system was designed around that requirement.
Plenty of people loaded up their homes themselves with four REN 1.0
phones without any special adjustment and without any problems. I
know of one rural subscriber who had six phones and had trouble, but
the phoneco did something at the pole and he was fine after that.
I suppose someplace there is an official standard stating the max
current RENs the phoneco is obligated to provide.
I don't know if the older 300 series or 1930s standalone ringer boxes
used more current than REN 1.0. Some ringers, such as outdoor units,
may need more current.
ArarghMai...@not.at.arargh.com
>On Jan 18, 1:05�am, ArarghMail001NOS...@NOT.AT.Arargh.com wrote:
>
>> IIRC, back in the old days, if you had more than 2 or 3 phones, the
>> installer opened the phones and did something to the ringer. �I think
>> he would adjust the tension on the ringer so that it needed less
>> current to work properly. �
>> This would be for ordinary 500 & 2500 series phones - ringer
>> equivalence 1.0A types.
>
>I've never heard of that practice. Note that on 500/2500 phones the
>subscriber adjusts the bell themselves to control loudness.
Loudness, yes. Except that by default, you can't turn the ringer off
completely. In order to do that, you have to open the phone, and bend
a litttle tab that's on the ringer assembly. Also, on that assembly
is a little wire with a 2 position holder that I saw being adjusted,
which I think is for ringer current. (It's between the two bells).
<snip>
Charles Richmond
My understanding was that the phone company would *charge* you
more if you had more than two "ringer equivalences" on the line.
Supposedly they can detect this on their end.
hanc...@bbs.cpcn.com
> > The phone line can support much more than two ringers, more like four
> > or five unless one lives far from the C.O.
>
> My understanding was that the phone company would *charge* you
> more if you had more than two "ringer equivalences" on the line.
> Supposedly they can detect this on their end.
A great many people had more than two extensions (REN 1.0) but were
never charged for them.
To be a problem, one had to have at least five REN 1.0, but I'm not
sure even that was an extra charge.
hanc...@bbs.cpcn.com
> Loudness, yes. Except that by default, you can't turn the ringer off
> completely. In order to do that, you have to open the phone, and bend
> a litttle tab that's on the ringer assembly. Also, on that assembly
> is a little wire with a 2 position holder that I saw being adjusted,
> which I think is for ringer current. (It's between the two bells).
A major feature of the 500 set was that it was automatically self-
adjusting for distance from the central office. Older sets required
some tuning. This was a significant labor saving issue.
Also, around the mid 1970s the phone company opened stores and
encouraged customers to install their own phones (this was prior to
Divesture) in an attempt to save on labor costs. Obviously phones
could not be adjusted.
I can't say for sure, but I strongly doubt that little 2 position
holder is for ringer current because I've seen far too many amateur
installations with many phones working just fine. Unfortunately, I
don't know what that little wire does. I've played with it and it had
no effect.
ArarghMai...@not.at.arargh.com
It seems to be the spring for the clapper. The position appears to
adjust the tension of the clapper. When I tried it last night, the
clapper seems to move more easily in one of the positions. The
position probably has little effect unless the available ring current
is very small.
I found some links to references about phones, but haven't taken the
time to download any of them:
http://www.paul-f.com/BSP.html Links are near the bottom of the page.
Walter Bushell
Charles Richmond <fri...@tx.rr.com> wrote:
> hanc...@bbs.cpcn.com wrote:
> > On Jan 17, 5:46 pm, Charles Richmond <friz...@tx.rr.com> wrote:
> >
> >> The other downside is that
> >> it takes *much* more current to ring the bell on your 1938 phone
> >> than to ring the modern phones, and that power comes directly off
> >> the phone line. ISTM that the phone company allows you *two*
> >> "ringer equivalencies" on your single number line, a "ringer
> >> equivalency" being the current it takes to ring a real bell in a
> >> telephone.
> >
> > The phone line can support much more than two ringers, more like four
> > or five unless one lives far from the C.O.
> >
> >
>
> My understanding was that the phone company would *charge* you
> more if you had more than two "ringer equivalences" on the line.
> Supposedly they can detect this on their end.
My father put an extra phone in and the phone company came and pulled
it. They used a Wheatstone Bridge on the circuits to discourage such
behavior.
--
A computer without Microsoft is like a chocolate cake without mustard.
Dav Vandenbroucke
wrote:
>The Feds said bring it up to code or don't reinstall.
I understand that. What I was saying was that they probably couldn't
find anyone who could have installed it in the 1950s way anyway.
D.J.
<dav_and_france...@compuserve.com> wrote:
>On Mon, 18 Jan 2010 15:48:29 -0600, D.J. <jollyc...@cableone.net>
>wrote:
>
>>The Feds said bring it up to code or don't reinstall.
>
>I understand that. What I was saying was that they probably couldn't
>find anyone who could have installed it in the 1950s way anyway.
Sure they could, this is in Mississippi after all.
JimP.
--
Brushing aside the thorns so I can see the stars.
http://www.linuxgazette.net/ Linux Gazette
http://www.drivein-jim.net/ Drive-In movie theaters
http://crestar.drivein-jim.net/ Jan 18, 2010
hanc...@bbs.cpcn.com
> > My understanding was that the phone company would *charge* you
> > more if you had more than two "ringer equivalences" on the line.
> > Supposedly they can detect this on their end.
>
> My father put an extra phone in and the phone company came and pulled
> it. They used a Wheatstone Bridge on the circuits to discourage such
> behavior.
To clarify:
Before the Bell System breakup ("Divesture") in 1983, almost all
telephone equipment was rented from the phone company (the first phone
was provided free). Note that regulators wanted it this way to keep
the most basic rates cheap at the expense of big users. Some people
who added on bootleg extensions had to pull them out. The phone
company had tests to determine total ringer resistance.
After 1983 subscribers could own their own phones and most did so.
After that the phone company did not care how many extensions one had
on their line.
Note that before 1983 the rental of an extension included all
maintenance for the set and wiring. After 1983 all of that was the
subscriber's responsibility.
Brian Boutel
>
> The only thing the 1938 phone has different is that the pulse
> cadence is Z; unique to Oslo and New Zealand, so the switch has
> to do a "tr '0123456789' 1234567890'"; or I will have to paste
> new digits on the phone.
Somebody will surely correct me if I'm wrong, but no NZ exchanges
support pulse dialling any more, so this is history. I'm actually rather
surprised that the US is so backward-compatible. Originally all handsets
were rented from the phone company, and allowing privately-owned
(approved) devices to connect to the network came after the introduction
of tone-dialling, so, possibly apart from a few early modems, there are
no pulse devices around to connect.
I'm not clear which systems you were translating between, but NZ, like
Olso, had, starting at the top of the dial, and going anti-clockwise,
9876543210, as opposed to the US/UK 1234567890, hence our 111 for
emergency calls (although 911 and probably 999 undoubtedly work, for the
benefit of those confused by foreign tv shows).
--brian
--
Wellington, New Zealand
"I don't respond to Christopher Hitchens in public, on the general
principle that you should never mud-wrestle with a pig because you both
get filthy and the pig likes it." -- Tony Judt
Morten Reistad
Brian Boutel <fa...@fake.nz> wrote:
>Morten Reistad wrote:
>
>>
>> The only thing the 1938 phone has different is that the pulse
>> cadence is Z; unique to Oslo and New Zealand, so the switch has
>> to do a "tr '0123456789' 1234567890'"; or I will have to paste
>> new digits on the phone.
>
>Somebody will surely correct me if I'm wrong, but no NZ exchanges
>support pulse dialling any more, so this is history. I'm actually rather
>surprised that the US is so backward-compatible. Originally all handsets
>were rented from the phone company, and allowing privately-owned
>(approved) devices to connect to the network came after the introduction
>of tone-dialling, so, possibly apart from a few early modems, there are
>no pulse devices around to connect.
I still find pulse dialling equipment around; but it is getting rare.
But it is still in support, using the right equipment.
I can even sell you channel banks that support it, with all the
1960-era frills. You can have high RENs too, but that requires
a power supply and line driver upgrade.
All of this is still in support from at least 4 vendors where you
can connect it to asterisk and/or yate or freeswitch.
It is not very expensive either, considering the age of the
equipment it can connect.
>I'm not clear which systems you were translating between, but NZ, like
>Olso, had, starting at the top of the dial, and going anti-clockwise,
>9876543210, as opposed to the US/UK 1234567890, hence our 111 for
>emergency calls (although 911 and probably 999 undoubtedly work, for the
>benefit of those confused by foreign tv shows).
There are numerous ways of assigning these. NZ and Oslo chose one
of the weirder ones.
-- mrr
Peter Flass
> Morten Reistad wrote:
>
>>
>> The only thing the 1938 phone has different is that the pulse
>> cadence is Z; unique to Oslo and New Zealand, so the switch has
>> to do a "tr '0123456789' 1234567890'"; or I will have to paste new
>> digits on the phone.
>
> Somebody will surely correct me if I'm wrong, but no NZ exchanges
> support pulse dialling any more, so this is history. I'm actually rather
> surprised that the US is so backward-compatible. Originally all handsets
> were rented from the phone company, and allowing privately-owned
> (approved) devices to connect to the network came after the introduction
> of tone-dialling, so, possibly apart from a few early modems, there are
> no pulse devices around to connect.
>
Actually, when AT&T broke up, customers had an option to buy their
existing phones which, since it was cheaper, many did. A lot of the
existing base was still pulse.
hanc...@bbs.cpcn.com
> Actually, when AT&T broke up, customers had an option to buy their
> existing phones which, since it was cheaper, many did. A lot of the
> existing base was still pulse.
Yes, it was a bargain. Further, subscribers could trade in an
existing phone for a brand new one and still pay the "used" price.
In 1983 and for a some time afterwards Touch Tone was an extra cost
option, so pulse remained quite common. It eventually became free.
Since plain landline phones are so cheap, it is likely the vast
majority of landlines out there serve Touch Tone sets. I don't know
the percentage.
However, many people have retained an older Western Electric (or
Automatic Electric) telephone for use in an emergency since the
popular cordless phones require house power while plain phones do
not. Other people have an old set hard wired into the wall and simply
never bothered to disconnect it, it still would work fine. Only when
there'd be a major house rennovation would people pull out a hard
wired phone. A household can mix Touch Tone and pulse telephone sets
on the same line.
AFAIK, the 'decoding' of pulse dialing is done by long-existing
software and adds no cost to the switch. The central office already
has to monitor the line status at all times (on hook or off hook or
flash) anyway. Further, a flash for Call Waiting or 3-way calling is
commonly used. Dial pulses are merely rapid on-off of the
hookswitch. AFAIK, almost all US central offices will support pulse
dialing.
Modern PBXs may not be able to support pulse dialing or even
traditional WE 300/500/2500 series sets.
jmfbahciv
> On Jan 21, 6:03 pm, Peter Flass <Peter_Fl...@Yahoo.com> wrote:
>
>> Actually, when AT&T broke up, customers had an option to buy their
>> existing phones which, since it was cheaper, many did. A lot of the
>> existing base was still pulse.
>
> Yes, it was a bargain. Further, subscribers could trade in an
> existing phone for a brand new one and still pay the "used" price.
>
> In 1983 and for a some time afterwards Touch Tone was an extra cost
> option, so pulse remained quite common. It eventually became free.
No, it was not free. What happened is the base price was increased
to cover the "extra" price of touch tone.
/BAH
Walter Bushell
<7724134a-e87f-4a32...@b9g2000yqd.googlegroups.com>,
hanc...@bbs.cpcn.com wrote:
> In 1983 and for a some time afterwards Touch Tone was an extra cost
> option, so pulse remained quite common. It eventually became free.
I think in the 1900s some places did not support Touch Tone dialing, as
I recall my parents were telling me that Touch Tone was 20 years in the
future in Lusby Maryland.
Dave Garland
> hanc...@bbs.cpcn.com wrote:
>> In 1983 and for a some time afterwards Touch Tone was an extra cost
>> option, so pulse remained quite common. It eventually became free.
>
> No, it was not free. What happened is the base price was increased
> to cover the "extra" price of touch tone.
Exactly. Sometime in the mid '90s my telco announced that it was
"lowering rates for the great majority of people". That meant, if you
were paying for Touchtone, you got a dollar off; if you weren't, you
saw a $4 hike in the base rate. I suspect it was smoke and mirrors to
conceal a hike in the overall rates.
It's true that by that time most people did have Touchtone. Many of
them were under the impression that a phone that had number buttons
required it, and had never noticed the little switch on the side that
said "tone/pulse".
Dave
jmfbahciv
I never ordered the touch tone service. At some point, the
functionality was there. I do remember my phone bill going
up because everybody had to have touch tone service from
then on. Mid 90's sounds right.
/BAH
hanc...@bbs.cpcn.com
> It's true that by that time most people did have Touchtone. Many of
> them were under the impression that a phone that had number buttons
> required it, and had never noticed the little switch on the side that
> said "tone/pulse".
That would only be newer phones. Older Touch Tones required a tone
equipped line set by the C.O. The oldest Touch Tone phones required
proper polarity or the keypad wouldn't work; polarity doesn't matter
for rotary phones.
From the 1980s onward, many people quietly found their phone line
accepted Touch Tone even if they weren't paying for it, but not
everyone.
In my case, my old house was served by a No. 5 Crossbar office and I
got free Touch Tone service. I moved new a house served by ESS and I
did not have it and had to pay for it. Around that time the pre-dial
5 digit long distance codes came out and I found rotary dialing 15
digits tiring.
In the 1990s my mother had me convert all of her phones to Touch Tone
since she was having trouble reaching businesses with their phone mail
jail menus that had become commonplace.
As an aside, in those years many local phone companies ceased
supporting mulit-party line service. First, they ceased offering it
to new customers, then they told the grandfathered existing customers
they were being upgraded to a private line. Since there were so few
party line subscribers by that point (the notice letters were
addressed by hand!) most effectively had a private line anyway by that
point. I'm not sure if any US phone company _today_ supports party
line service, even for grandfathered customers.
Charlie Gibbs
writes:
A side effect of Touch Tone capability was improved pulse dialing
performance. My first modem was a 300-baud manual model where you
had to dial the number yourself, then turn on the modem when you
heard the carrier from the other end. I hacked a relay into the
phone line side of it, and wired it up to be driven by the DTR line.
A friend wrote a driver for MEX, the CP/M terminal emulator program
we were using at the time, and I was able to auto-dial. The driver
assumed that the line was busy if it didn't see a carrier after a
certain length of time, so I was able to let it hammer away at busy
BBS numbers until it got through on one of them.
I found that on my Touch Tone line, my hacked-up modem was able
to pulse dial at 20 pulses per second, making it almost as fast
as tone dialing.
--
/~\ cgi...@kltpzyxm.invalid (Charlie Gibbs)
\ / I'm really at ac.dekanfrus if you read it the right way.
X Top-posted messages will probably be ignored. See RFC1855.
/ \ HTML will DEFINITELY be ignored. Join the ASCII ribbon campaign!
Michael Black
> I found that on my Touch Tone line, my hacked-up modem was able
> to pulse dial at 20 pulses per second, making it almost as fast
> as tone dialing.
>
When I got my Radio Shack Model 100 in 1985, there was a switch
to select the speed of the pulse dialing (it did not do touchtone).
I put it to the faster rate, and ended up with mis-dialled phone numbers.
Never since have I tried the faster rate. To this day I still don't
have touchtone, there's still a premium fee here for it. A few years
ago, maybe as much as a decade, Bell wanted to raise the rates so
everyone got touchtone, but they weren't allowed, so it remains a premium.
At this point, one ought to consider they save money with touchtone and
the cost of the switchover is long passed, so they should just let
everyone have touchtone capability without an increase.
Michael
Charles Richmond
I use Vonage. They do *not* charge extra for "touch tone". ;-)
hanc...@bbs.cpcn.com
> I found that on my Touch Tone line, my hacked-up modem was able
> to pulse dial at 20 pulses per second, making it almost as fast
> as tone dialing.
Faster pulse dialing had nothing to do with Touch Tone. It was a
function of _relatively_ newer electro-mechanical switchgear.
Years ago some kids in my high school tinkered with their home phone
and discovered they could make their dial go at 20 pps--and that it
worked. I also saw that on a large business PBX switchboard the
operators had 20 pps dials.
When modems with adjustable settings came out more people were able to
discover this easily by a simple software setting.
The incoming registers of crossbar switches* were able to receive
pulses at 20 pps and of course ESS registers could handle it. Why the
phone company didn't speed up the dials of subscribers on such
switches I don't know; perhaps they were afraid of confusion with SxS
customers. Anyway, by the time personal computers were popular, most
subscribers were served by a crossbar or electronic switch.
People served by the older step-by-step switches were stuck with 10
pps as that was the speed of the switchgear.
In smaller towns, some SxS customers did have an advantage--the need
to dial only 5 digits for local calls.
*I don't know if the registers of panel switches could handle 20 pps.
But note that No. 1 crossbar came out in 1938 for cities, and then No.
5 in a big way in the 1950s.
hanc...@bbs.cpcn.com
> On Mon, 25 Jan 2010, Charlie Gibbs wrote:
> > I found that on my Touch Tone line, my hacked-up modem was able
> > to pulse dial at 20 pulses per second, making it almost as fast
> > as tone dialing.
>
> When I got my Radio Shack Model 100 in 1985, there was a switch
> to select the speed of the pulse dialing (it did not do touchtone).
> I put it to the faster rate, and ended up with mis-dialled phone numbers.
You were probably served by a step-by-step switch which couldn't
handle higher speeds.
(Bell experimented with higher speeds but found it led to excessive
wear on the switchgear.)
> Never since have I tried the faster rate. To this day I still don't
> have touchtone, there's still a premium fee here for it. A few years
> ago, maybe as much as a decade, Bell wanted to raise the rates so
> everyone got touchtone, but they weren't allowed, so it remains a premium.
> At this point, one ought to consider they save money with touchtone and
> the cost of the switchover is long passed, so they should just let
> everyone have touchtone capability without an increase.
They don't 'save money' with Touch Tone. Indeed, a modern telephone
switch has to have all the hardware necessary to decode dial pulses
anyway, while Touch Tone requires a filter to decode the audio tones.
But the cost of those decoding filters are not much these days.
Morten Reistad
<hanc...@bbs.cpcn.com> wrote:
>On Jan 25, 11:13�am, "Charlie Gibbs" <cgi...@kltpzyxm.invalid> wrote:
>
>> I found that on my Touch Tone line, my hacked-up modem was able
>> to pulse dial at 20 pulses per second, making it almost as fast
>> as tone dialing.
>
>Faster pulse dialing had nothing to do with Touch Tone. It was a
>function of _relatively_ newer electro-mechanical switchgear.
And these switches are really to the point in a.f.c. The 2.nd ISDN
switch generation, sold ca 1992 onwards does all of this decoding
in software, with just a little filtering and conditioning on the
line.
So do the modern switches of today. Lots of voip based switches actually
support pulse dialling on FXS lines. This even includes a few ATAs.
But the lower limit for a reliable pulsing is around 70 ms per pulse
on these software driven things.
That is around 13 pulses per second, with ca 30ms make and 40ms break.
Much lower than that, and picking up random noise becomes a problem.
>Years ago some kids in my high school tinkered with their home phone
>and discovered they could make their dial go at 20 pps--and that it
>worked. I also saw that on a large business PBX switchboard the
>operators had 20 pps dials.
That is really pushing it. 25/25 can work, but it needs a well tuned
switch. Installers don't tune lines anymore.
>When modems with adjustable settings came out more people were able to
>discover this easily by a simple software setting.
>
>The incoming registers of crossbar switches* were able to receive
>pulses at 20 pps and of course ESS registers could handle it. Why the
>phone company didn't speed up the dials of subscribers on such
>switches I don't know; perhaps they were afraid of confusion with SxS
>customers. Anyway, by the time personal computers were popular, most
>subscribers were served by a crossbar or electronic switch.
The cheaper electronics in phones would have problems going much
faster than it actually did.
>People served by the older step-by-step switches were stuck with 10
>pps as that was the speed of the switchgear.
Or not even that. 135 ms seemed a norm, that is around 7.5 pulses a
second. That is around the lower limit of how slow it can go without
getting detected as a break ("R") signal.
>In smaller towns, some SxS customers did have an advantage--the need
>to dial only 5 digits for local calls.
>
>
>
>*I don't know if the registers of panel switches could handle 20 pps.
>But note that No. 1 crossbar came out in 1938 for cities, and then No.
>5 in a big way in the 1950s.
ISTR 70 ms as an older spec for pulse dialling, that would be around 13
pulses/second. But that is from old memory.
-- mrr
hanc...@bbs.cpcn.com
> >Faster pulse dialing had nothing to do with Touch Tone. It was a
> >function of _relatively_ newer electro-mechanical switchgear.
>
> And these switches are really to the point in a.f.c. The 2.nd ISDN
> switch generation, sold ca 1992 onwards does all of this decoding
> in software, with just a little filtering and conditioning on the
> line.
The incoming registers of panel switches (which date from the 1920s)
may have been able to handle 20 pulses per second. I don't know for
sure.
But the No. 1 crossbar, dating from 1938, certainly could handle 20
pps and did so. And certainly the 1950s No. 5 crossbar. I don't
believe the lines were specially conditioned for this faster pulse
rate, although the loop was relatively close to the central office
(about 1-3 miles).
All of them used relay logic, not electronics.
All electronic telephone switches used software decoding. Software
also had to handle 'flashing' to activate special features and of
course hang-up.
Coming into the late 1900s, modems could be set to run at 20 pps. I
so set mine and it worked fine. My modem also allowed modifying the
'make/break' ratio, but I never touched that. I believe that varies
between North America and other countries, so a telephone set built
for service elsewhere might not work well in the U.S.
Charles Richmond
Now how about the *other* end??? The "smart" phones of the 1990's
often used a 4-bit microprocessor (TMS1000 ???) to handle the
memory. Our Panasonic phone could store 20 phone numbers of up to
16 digits each. In such phones, the 4-bit microprocessor was often
used to generate the "touch tone" tones. It would *not* surprise
me if the microprocessor generated the "ring" of the telephone.
The whole phone was built around this one little microprocessor.
Radio Shack put out a small book (about 90 pages) describing how a
"smart" phone could be designed around a 4-bit processor.