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- private linemagazine
- private linemagazine
a journal of inquiry into the telephone system
December 12, 1999
E-mail me! -- tom@privateline.com
- FAX (707) 220-1011 -- Please send in high res or fine mode
- ?? SEARCH PRIVATELINE.COM ??
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(NB: The free newsletter service I had been using will be discontinuing operations in mid-October -- I am looking at other options.) |
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| [ p.l. No. 1 ] [p.l. No. 2] [p.l. No. 3] |
| [p.l. No. 4] [p.l. No. 5] [p.l. No. 6] |
| [p.l. No. 7] p.l. No. 8 p.l. No. 9 |
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p.l. No. 10 [p.l. No. 11] [p.l. No. 12] |
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| Cellular telephone basics |
| Celular de los fundamentos |
| Manual test mode scanning |
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| Outside Plant -- local loop |
| Telephone & Cellular History |
| Early Work on Dial Telephone Systems by R.B. Hill (illustrated) |
| The Early Years of the Strowger System by R.B. Hill (illustrated) |
| Canadian Telephone History by Mark Cuccuia |
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private line information |
| private line back issue ordering information |
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Encryption |
| Rich Adams' encryption basics |
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Graphics |
| Telephone smut |
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Sounds |
| The Voice of private line |
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Books and Links |
| My telephone book picks |
| Links page |
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Miscellaneous |
| Espanol |
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Thanks to Damien Thorn for hosting this site! |
Here we go again -- Pair Claim Cracking Cellular Code
The wireless industry has long assured people that GSM's voice encryption algorithm prevents unauthorized snooping. Either by ignorance or deliberate falsehood, this was a lie Two people with modest means recently broke an older version of the GSM routine. It must be assumed that the NSA and other intelligence communities, with their vast resources and the best crypto people in the world, long ago cracked that code and have been monitoring conversations for years. No doubt they are monitoring under the new version as well. From yesterdays' A.P. report written by Jessie Seyfer,
"Two Israeli researchers claim to have cracked a wireless encryption method that protects the privacy of phone calls made with the most widely used cellular technology outside the United States.
A consortium of digital cellular providers dismissed the claim, saying it was an "academic exercise'' based on an outdated encryption formula. Adi Shamir and Alex Biryukov of the Weizman Institute in Rehovot, Israel, did not formally announce their findings, which they plan to publish, but Shamir confirmed the claim Tuesday in a telephone interview from his office in Israel."
GSM voice encryption has not been cracked before. At least, no one admitted it. Rather than an academic exercise, these men broke the code over the air, with an intercepted transmission. This was not done in a laboratory. Industry experts have told me over the years that the GSM code was secure; it now appears that at least in this older version is not. It now seems likely that the NSA and various world intelligence forces have been intercepting and decoding GSM traffic for some time.
Although most monitoring is probably done at the wireline level, or compromised by the occasional rouge system technician, I am not addressing that issue here. A GSM phone was cloned last year for the first time in a lab. Industry experts assured me this was of no significance and that over the air cloning was impossible, although one hacker outlined for me a method to do just that. Now that that voice encryption has been compromised over the air I am, regrettably, less and less trustful of the wireless trade. You should be too.
Air Pressure Primer
Thanks to Mud Demon for this great link: http://www.airtalk.com/_primer.htm This primer discusses air pressure equipment, which telephone companies use to keep underground and aerial lines free from moisture. It's a fascinating and little known aspect of telephony and it will give you more insight into what makes up the local loop and outside plant.
I've tried defining OSP before. Mud Demon comments that
"where I work, the outside plant extends up the tip cables from the vault
to the termination point at the coils on the main distribution
frame.
Anything out from the coils is considered "outside plant" and is
maintained by our group. Also the air compressor/dryers, pipes, meter and
pipe panels, computer, and even the 48 volt power supply for the computer
are considered "outside plant" even
though they are inside."
Inside means inside the central office, most typically in
the cable vault below the building. One thing outisde the primer article's
scope are the gas bottles you see tied to telephone poles on the outskirts
of some cities. These must also be used to keep lines dry. I asked about
this and what kind of gas they might use. He replied that "Nitrogen is
inert,and relatively inexpensive. Liquid nitrogen
is also inert, and
relatively compact, but not used much. Bottles lashed to poles are a sign
that an air pipe system is not in place. To achieve a dual feed system
without an air pipe, there must be a source of some pressurized gas at the
end of the run, so bottles are placed. By comparison, with an air pipe
system such as the article describes, air pipes routed through the duct
system provide pressurized air at the end of a cable run."
Please check out the primer. Comes complete with graphics
and diagrams and is easy to read. http://www.airtalk.com/_primer.htm
A nice independent telephone site
I enjoy visiting independent telco sites. They are more personal than large telecom sites, often including history pages, something many coporations don't bother with. Some company history pages, in fact, constitute the first widely published record of their operations and as such make up a valuable part of telephone history . The Magazine Telephone Company of central Arkansas is a good example of what I am describing. Here's a little of their friendly history from their site-- please check it out:
http://www.cei.net/~magtel/Magtel/heritage.htm
"Also in 1940, the company that contracted to build the Blue Mountain Dam contacted the Telephone Company. The builders asked Henry if he would build a telephone line to the dam site. Henry hired two local men, Autry Sloan and Dick Roberts, to cut down cedar trees, dig holes, and set poles out to the dam. Henry strung two circuits of wire on the poles. One circuit was to serve the dam. The other circuit was to serve Blue Mountain and Waveland. The Blue Mountain - Waveland circuit served 20 subscribers and started the growth of service to those areas.
December 7, 1941 marked several changes in the Stone household. With the outbreak of WW II, the Stones were frequent hosts of spouses and families of service men and women. People would be in the home at all times of the day and night; anxiously trying to have calls completed to loved ones around the world. During the night, Henry would pull their bed up close to the switchboard so that Anna could answer calls without getting out of bed.
After the end of WW II, the R.E.A. System was introduced to the area. This electrification project induced noise into the one wire magneto system that was currently in use by the Telephone Company. Henry converted the magneto system to a new system called common battery. Instead of just one wire, common battery required two metallic wires for each circuit."
I'm still here
Sorry for neglecting the site; I am working on starting a company. For the last month and a half I've been working on the business plan and now we are taking first steps to get the company developed. It is not about telecom but I will let you know when we go online. Again, sorry about not writing more here but I just have to get this work done. I am still answering all of my e-mail and I welcome more. More later . . .
One of the best telecom magazines is also free
Ericsson's ON magazine recently launched. Check out the on line version and subscribe to the much better hardcopy magazine by going here: http://www.ericsson.se/on/. Some of these stories are the kind of thing I would have loved in my old magazine, had I the budget, the time, and the people. Less technical than the Ericsson Review (also free and essential), ON's design is lively while not overwhelming. What Wired doesn't look like but should. If you are really into new technology I strongly urge you to get both publications and even think of getting on Ericsson's PR e-mail list. You may not be able to keep up on all the telecom companies out there, but these materials will keep you informed on what is possibly the leading telecom company in the world. You'll get a look at the wireless future before it happens.
Even more telecom manual scanned
Well, the telecom manual is getting much more detailed. Click here to view chapter four. Click here to look at part one or here for part two or part three. I also have scanned a wonderful telco glossary. It is a huge (178K) file but once it loads you can save it as a text file or in any format you wish.
Is there a difference between digital cellular technology and digital PCS?
The similarity is that all modern radio-telephone service is, for the most part, cellular radio. A base station provides coverage within a small geographical area called a cell. Networking many of thos stations together allows roaming between the individual cells. This wireless wide area network lets a carrier provide coverage to a city or a town. Cooperative agreements with other carriers allow people to roam outside their normal coverage area. No matter how the radio works, be it PCS or conventional cellular, no matter the enabling transmission technology, say TDMA or CDMA, it is all cellular radio, since base stations and cells make up a wireless network.
PCS generally refers to cellular radio at higher frequencies. PCS is "all digital" compared to conventional cellular which is a hybrid of analog and digital routines. Being purely digital, though, is not necessarily a good thing. Quite often the all digital services lack coverage since more base stations are required. As wireless evolves the different services may operate on high and low frequencies as needed, thus blurring the defining lines between the technologies.
AT&T's IS-136 service, for example, an all digital evolution of conventional cellular, can operate on high and low frequency radio bands as needed. Depending on what the local carrier offers, it even changes its operating method, dropping back to analog cellular service where digital service isn't provided. Thus, IS-136 provides many "PCS like" services where it can, and in areas where it can't, it at least lets you talk and complete calls. I am a fan of this system.
GSM or PCS, besides being all digital, and designed in Europe with no thought of being compatible with conventional cellular, do differ from cellular in the way they make and send calls. The difference is in the details. But in the end it is all cellular radio.