Q. What's the difference between a Class 5 and a Class 4 office?

Although Class names aren't really relevant anymore, so many old telephone books mention them that I should explain them a little.

A Class 5 office is often called an End Office, or sometimes the central office. It is always the local switch, that is, the switch nearest the customer or end user. It serves the local loop. The calls you make from your home go to a class 5 office. Your DSL line is connected to a Class 5 office. A Class 4 office was or is always a toll switch, that is, a long distance switch. It takes the traffic from class 5 offices and puts them into the long distance network. Many Class 5 offices are connected directly with each other, no switch required to transfer a call. But for those CO's not directly connected the class 4 switch does the job. If the class 4 switch just connects central offices together the switch is called a tandem.

Before 1984 and the breakup of the Bell System, switches went all the way up to Class 1, which were regional long distance switches. In America I think we had only ten of these. Switching obeyed a strict hierarchy. Nowadays the switches pass traffic between each other at the lowest level possible. The old hierarchy is no longer in place. So, the Class 5 office is the local switch, all of the rest are long distance switches. But the class names really don't apply and we now have far fewer kinds of toll switches. If you want to see what the old network looked like, in a simple diagram, click on this link to view a really big file. But don't get confused, Class names are twenty years out of date.

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I discovered I have a number of brochures for early MTS and IMTS car telephones. One of these features "Pushbutton dial", a proprietary Motorola system pre-dating DTMF and pitched to rural REA co-ops as solving the issue of automatic dialing from mobiles (in order to eliminate a salaried cord-board mobile operator.)

Click on image to enlarge

As far as I know, PB dial was never implemented by any Bell affiliates. It is the same as MTS on land-to-mobile, but mobile to land in the automatic mode involves tone dialing in a strange system where the key stays depressed until the tone duration (preset) has been reached, at which time it pops up to allow you to dial the next digit ! The tones are not DTMF.

It was marketed as a system which prevented mis-dialing because the CO either got the tone or it didn't, unlike a rotary dial where a noise burst could mask one of the pulses and give you a wrong number.

Attached is a photo of the Motorola pushbutton dial control head. The handset hung up separately in this model. The side has a metal tag which says "U.S. AEC" leading me to believe this was used in a private government radiotelephone system in Southern California. Later models, at least in the brochures, show the handset hung up across the face in a cast aluminum cradle. There was also a key lock in that cradle, whereas this one has the lock on the front panel. The photo doesn't really show it, but the panel is actually banked, sloping back on the top edge. Nonetheless, quite ugly compared to the Bell System's MJ control head.

Geoff

Editor's note. The famed industrial designer Henry Dreyfuss styled the MJ control head. No one at Mot could compare to his designs.

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Click to enlarge (143K). From Ericsson's On magazine (external link). Now you know why telephone companies started putting wires underground. Can you imagine this wire plant after an ice storm?

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The Bell System was world famous for its industrial design research. Click on this link to see what they studied for operator consoles (167K). This diagram shows a stylized woman at the seat of their new cordless switchboard. Before 1972 no switchboard was designed with men in mind, there being no male operators. As JR Snyder Jr. relates, "I'm a small guy, 5'7'' and now almost 160, back then I was only about 128 lbs and I didn't have many problems at the cordboards. But any guy 5' 10' to 5'11' or over was pretty uncomfortable. The boards were sized for women, in fact not being over a certain height and size was a job requirement, sort of like airline stewardesses."

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A single cellular radio standard makes common sense but not business sense. Ericsson's On magazine (external link) this issue describes many reasons why operators will continue working different, incompatible cellular schemes across the globe. In years past a single standard (internal link) seemed absolutely necessary given the growth of different wireless systems. Today's mobile handsets, though, are becoming so versatile that they may soon adopt to any wireless scheme found. Without changing expensive infrastructure a carrier could thus operate several different technologies in a single country. A benefit to customers, a benefit to the carrier. Read more below and then at the On site.:

"Operators would often choose a standard because they felt it gave them an advantage over the competition,” says Yankee's Marshall. Now, the technology split in each nation and region varies enormously. At one extreme, the GSM family has a monopoly in Europe, with CDMA holding a similar position in South Korea.

But Brazil, India, Australia and Japan and other countries, competing network standards are surviving the transition to 3G. Other factors have come into play in markets such as Australia -- where CDMA was adopted because of its superior coverage capabilities," says Marshall. "In Japan, PDC is the 2G technology, so operators could effectively go either way. NTT DoCoMo is hot on WCDMA and KDDI is CDMA2000,"says Marshall.

There are a variety of reasons why neighboring network operators will opt for incompatible hardware. Market advantage is one, legacy issues [existing, older systems] are another, regulatory issues a third." Some have roaming agreements where they want others to roam on their networks, and some don’t want competitors roaming on their networks," says In-Stat’s Nogee.

This despite the fact that commentators such as the Yankee Group's Marshall say that, technically, CDMA technology is more cost-effective and easier to implement. But, he emphasizes, technical issues are not a useful gauge for strategic decisions.

So, technology is not the deciding factor over operators'choice. For all that, mobile telecommunications will never again be the patchwork it once was. Initially, there will be teething problems in those countries and regions with more than one technology. "There will be some limitations in terms of interoperability and roaming," says Marshall. But it is unlikely that there will be one standard across the globe: "There really is no reason to have just one," says In-Stat's Nogee.

But probably not for the eight or 10 standards we once had. Currently Japan, Europe and the U.S. have different TV standards, and that has worked just fine." For all that, the situation will settle. Twin networks will remain in some countries, says Marshall. "However," he says, "over time I think that we will see increased convergence on the device side so that it becomes less of an issue." Ultimately, then, handsets will be the great leveller, making network issues transparent to the user, as they should be.

Ericsson's On magazine (external link) Page 37 and Page 38

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Peter Pfeiffer reports on Nextel's financial shenanigans:

http://www.theresearchsource.net/canon3.htm (external link)

Peter and I are e-mailing each other. I'll have more on this story next week.

April 15, 2004

Finally!, a quality company to answer your cell site leasing questions. Ken Schmidt has been very helpful to privateline.com readers in the last two weeks and I am sure that will continue. Visit my page about his company. (internal link)

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Ken Schmidt has been very helpful to privateline.com readers in the last two weeks and I am sure that will continue. Visit my page about his company. (internal link)

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A nice site on T1 (external link)

Coming later this week. A good source for help with your cellular site lease problems. And perhaps a way to market the property you want to lease out.

Incredible site on telephony basics, an entire course on telephone basics. Done by the U.S. military and quite comprehensive. Click here to go there. (external link)

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Q. Why does the local loop operate at -48 volts?

A: (From Cowboy Frank)

48 volts came about because of the availability of 12/24/48 volt batteries which was the system that was used some years ago to deliver a reliable DC power supply. 12 to 24 volts was too low to do a decent job of delivering over the wires, and 60 volts was considered just a bit too dangerous and unnecessary. Almost impossible to get bit with 48 but you can get a substantial, but not actually deadly, charge from 60 volts. Just ask any cable TV service technician (like me) who has had to work on a charged cable in the rain.

As far as the + vs. - I don't know for sure, but it seems to me the Tip was charged with the - current (which was also grounded) to help protect the circuit and operators on a plug type switch board. It would have been too easy to touch the tip of the plug to some ground metal somewhere which would have shorted out the circuit and possibly blown fuses in the switchboard. More difficult to short out the ring on the plug.

A. (From Tom Farley) This plays into Ohm's law and economics. You want the least expensive wire using the least amount of power to get the job done. I once came across an article that said the average length of Bell System local loops was 2.9 miles, roughly 15,480 feet. According to the telephone FAQ at my site, No. 22 wire, the most commonly used, should have 246.9 ohms of resistance over that length. The FAQ goes onto say the Bell System wanted at least 20 milliamps for the local loop to work. If you multiply .20 x 246.9 you come out with 49.38 volts. Close enough. See the Ohms' law calculator below.

http://www.csgnetwork.com/ohmslaw.html

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Q. Tom: Can you link to us? We're an on-line cellular store that can offer you good money for every mobile activated through your site.

A. Aside from linking to Amazon for mobile telephone sales (internal link), I have to decline any such offers. It's too difficult to check the reliability of every company that wants a link over. Also, customers today aren't getting served as well as they should be by many cellular sales web sites. In my area both SureWest Wireless (external link) and MetroPCS (external link) offer better rates than the major carriers yet they're not offered through most secondary sites. This is the same thing with Jet Blue or Southwest airlines, wildly successful services that many like but ones you won't find offered on Travelocity, Expedia, or Orbitz. You usually have to go directly to their sites rather than through a middleman. But thanks for the interest.

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Sony Ericsson now produces a toy car you control with their Bluetooth enabled phones. Run it around up to 30 feet from your mobile. While certainly cool looking, and obviously a great deal of phun, I think this new accessory points not toward entertainment necessarily but to how we must rethink what we want our wireless phones to do. With Bluetooth and other local wireless technologies our mobiles cease being standalone, voice-oriented devices. They can now act with local computer networks, which in turn can operate with a world of networks. What's next? I don't know. But through wireless we are quickly bringing computing power everywhere. It will be fascinating to see what the coming years bring.

Read a review of this device by clicking below:

http://www.mobile-review.com/review/sonyericcson-btcar-en.shtml (external link)

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