POTS circuits

[Brian Roth]

For the newbies, POTS is Olde telephone jargon for Plain Old Telephone Service.  IE, copper from the CO (Central Office) to the telephone set in your house/office.

Nowadays, most everyone uses a cell phone, or for a "wired" phone, something via the cable company or other internet provider.

But, cell and VOIP telephone service can be FAR less reliable than the new-fangled options.  Cell service is radio, and can get jammed up due to heavy call volumes or cell towers being blown down/power losses during storms.  VOIP ASSumes that your cable router has power, and in the case of Cable phone service, the "magic box" mounted on the side of your house has juice left in the rechargable battery pack...usually 4 to 8 hours of talk time.

POTS lines are powered from a big bad stash of batteries with diesel backup gens located at the CO.  POTS lines stay active, unless something breaks the copper pair going to the destination.  Yes, a cordless POTS phone relies on having AC Mains to power the base/handsets, but other phones are "passive" in terms of making a call to 911 when the cell lines are jammed, or the batteries in the VOIP box runs out of juice.

Bri

PS, POTS lines are an "ultimate" in star topology.  The copper pair home-runs from the telephone set back to the CO.

 

[PRR]

> POTS lines are powered from a big bad stash of batteries with diesel backup

Actually: from the local electric utility company, backed and smoothed by BIG battery room, with engine behind that. 

However *before* that, the CO was passive. Each subscriber had a talk-battery, and a hand-crank for ringer.

 

[Brian Roth]

I stand corrected.....when "OG+E" (my local electric utility) is up and running, the rectifiers powered from them charge the Big Stash of batteries at the CO.  During a utility outage, Ma Bell runs the POTS stuff from the batteries, and then fires up the diesel gens....AFAIK.

Bri

 

[CJ]

those battery rooms are scary! i installed a power meter at a site in Indiana, big brick building with a basement full of zillions of batteries, not too big, about 2 feet high and a foot thick, white plastic that you could almost see thru, all wired up to big copper buss bars, the bars were exposed so do not drop any tools! probably 100 yds of + and - bars a foot away from each other, 

there were lots hydrometers and big plastic jugs of acid everywhere, no vents, no ventilation for any fumes, i guess that's why they used a brick building,

actually the scariest part was the saleman who drove me to the site in a rental car on the iced up roads at night, he smelled like a fifth of wild turkey and i was the hostage,

 

[Brian Roth]

EGADS...  my recollection of the "battery farm" at a CO was DECADES ago when I was a Boy Scout...

I clearly recall the clattering of the "step by step" switching.....

http://www.youtube.com/watch?v=xZePwin92cI

Also, systems used a crossbar switching as well...

Bri

 

[Brian Roth]

http://en.wikipedia.org/wiki/Number_Five_Crossbar_Switching_System

Bri

 

[CJ]

Brian, you are the Man!

i have been looking for this movie for about 30 years!

found it by backtracking that video you posted to the website mentioned at the end,

Brattain explaining the transistor, saw it in electronics class around 1970,

it is the best explanation of the transistor out there, and right from the horses mouth!

i even went to the school district to see if they had the B and W film, but no luck,

Thanks!  ;D ;D ;D ;D ;D

http://techchannel.att.com/play-video.cfm/2011/6/29/AT&T-Archives-Dr-Walter-Brattain-on-Semiconductor-Physics

http://techchannel.att.com/play-video.cfm/2011/8/22/AT&T-Archives-Genesis-of-the-Transistor


thanks again!  and sorry for the OT,

cj

 

[Brian Roth]

Egads  I forgot all that college math...

But, I was thinking about how circuits were switched when I placed a phone call...eons ago....

Bri

 

[ruffrecords]

POTS is still the de facto land line connection in the UK and old dial phones still work. Most people in the UK get their internet connection down the copper by ADSL.

Cheers

Ian

 

[Brian Roth]

Approx 30 years ago, I was the "golden boy" at a  local company.  I was chief engineer for the 24 track studio which made ad jingles.

Along the way  "well, Brian can figure THIS out..."  so I also was the person who called the plumber when toilets backed up, called other vendors when the HVAC systems screwed up and I couldn't fix it....

Along the way, I learned "Ma Bell tip and ring" systems, and specified and maintained Mitel PBX systems in multiple company offices  from approx. 1982 through approx. 1998.  Around 1999, "corporate" dictated new Nortel  PBX systems, which were stupidly expensive and crazy to maintain.

The Mitel stuff was sold off..and in a mere few years, the Nortel junk was....junked.

BUT, the current Cisco VOIP system is pretty cool....as long as the entire network is functional.

Bri

 

[Brian Roth]

As for me here at "Camp Chaos" I still pay a monthly charge for a copper pair "in case the casa catches on fire".

I trust VOIP/cell phone/etc about as far as I can throw this hacienda down the block.....

Bri

 

[horvitz]

Goodness, I thought I came here to get away from this stuff!  :

You'll be pleased to know Bri, that even in modern brand new Cisco VOIP systems, you'll still see a couple of POTS lines floating around for emergency services.  At least the ones I work on, anyway.  Make sure that 911 always goes out the POTS so that you are guaranteed to be routed to the correct response center.  Nothing like dialing 911 when you are having a heart attack at your desk and going to the emergency center three towns over because that's where your PRI is served out of.  Also, in a pretty large system that I worked on recently, they installed switchers so that if the power went out and the local UPS died (30 minutes was the spec) then an analog phone in each office would be directly connected to the POTS so they would have some sort of dialing capability.

Old, dumb, and reliable.  Exactly what you want when the crap hits the fan.

 

[PRR]

> when "OG+E" (my local electric utility) is up and running

Whenever possible, Ma took two power feeds. Separate sub-stations, if affordable. In rare cases, when a CO was near a boundary, they could reasonably take power from both "A"G&E and "B"G&E. So if one died, the other might stay up. (Of course town utilities grew and merged, or at least took power from the same large sources, so this went out of style.)

Grounding those buildings and rooms was crazy.

 

[iomegaman]

Many years ago I was  project manager on a Federal Renovation project at the Grand Canyon...stacks and layers of engineers and architects were involved and so in wisdom they replaced all the copper to the five buildings (training center apartments) with fiber optic cable...we had to pull out all the copper and replace it in the trenched tubes...massive challenge for our electricians...but as per spec we did it...

Only to find out near the end of the project that Federal law requires a copper line be present in each building so that in case of fire a land line can make the call and NOT some new fangled VOIP with AD/DA converters...and as per project we had PULLED all the copper out of the tubes...

It added about 150K just in digging and trenching through the rock to relay the old copper pair to each building...copper that had been there before the brilliant engineers and architects told us to pull it all out...

Your tax dollars at work...

 

[okgb]

I remember when you could do a phone interview [ 90's ? ] and it could sound pretty good ,
Horrible what they accept from phones  for  " broadcast quality " these days

 

[CJ]

does the Blue Box work on pulse tone systems?

 

[ppa]

POTS is still the de facto land line connection in the UK and old dial phones still work. Most people in the UK get their internet connection down the copper by ADSL.

Cheers

Ian

same thing in Italy

 

[JohnRoberts]

Time for funny POTS stories... I have two...

#1 I had a bad connection somewhere in the path for my office extension at Peavey... The ring voltage would break through the oxidation and ring, but then the call would drop...  When I would call the snarky switchboard operator to report the line problem, her answer was "well how are you calling me dearie?"  Arghhh. Linemand found a bad wire up on a pole between my building and the main office.

#2 I had a DSL problem where the DSL was piggybacked over the POTs lines. However both can kind of work, but with POTS service it gets very noisy, and the DSL can be intermittent. I couldn't convince anybody to come out and look at my POTS wires to fix DSL and had to lie to them, and agree to pay if i was wrong. They no doubt had caller ID so could see I was calling them on the reported "bad" line. Of course they found where a squirrel had chewed my wires.

POTS when men were men and phones were phones, engineered to last for a very long time.   

JR

 

[jdiamantis]

Well, they may LOOK like POTS lines, but most areas here near and inside D.C. use copper from the nearest D-mark or pedistal to your dwelling or office, and are sent digitally the rest of the way to the C.O.

These new packetized circuits behave totally differently than your regular POTS line, so any modems, including fax machines, operate sometimes with great difficulty.

With they way the telco's don't maintain the lines, it's any wonder we have any connectivity at all.

Not many "fun" stories, but lots of recent nightmares dealing with this in a radio broadcast environment.

jD

 

[Brian Roth]

AFAIK, my hacienda is still copper connected to the CO, which is maybe 1/3 mile due east away "as the crow flies".  I do know there is at least a mile of copper between here and there based upon some info I dug up several years ago when researching any DSL options.

In my case, the entire neighborhood was built circa 1970 with buried cable, and after 18 years here I now know that my  copper goes more than a bit west, turns north, then goes back east to the CO.  Hence the length.

Interesting comment re. NOVA.  For more than a few years, I've been involved with a broadcast operation in "Old Town" Alexandria, VA (Torpedo Factory area, which makes sense only to the locals...) and the constant fights with C&P  (Cheap and Pitiful <g>) Telephone Co.

In NOVA, I've fought with POTS lines for the Telos multi-line "call in" system, as well as ISDN for the other Telos requirements.

Bri