TELECOM Digest Wed, 4 Jan 95 08:33:00 CST Volume 15 : Issue 5 Inside This Issue: Editor: Patrick A. Townson Re: Protest of New Compuserve-Unisys GIF Usage Tax (Jack Hamilton) Re: What is a T1 Line? (Joseph H Allen) Re: Britain-Japan Fiber Cable (Wally Ritchie) Re: Finland Data Transmission (Wally Ritchie) NANP 800 Numbers From the UK (Clive D.W. Feather) Cellular Billing Services (Raymond S. VanderBok) Cell One NY/NJ Eliminates Daily Roam Charges (Stan Schwartz) Summary: Telecom Texts (David P. Wiltzius) TELECOM Digest is an electronic journal devoted mostly but not exclusively to telecommunications topics. It is circulated anywhere there is email, in addition to various telecom forums on a variety of public service systems and networks including Compuserve and America On Line. It is also gatewayed to Usenet where it appears as the moderated newsgroup 'comp.dcom.telecom'. Subscriptions are available to qualified organizations and individual readers. 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Any organizations listed are for identification purposes only and messages should not be considered any official expression by the organization. ---------------------------------------------------------------------- From: jfh@crl.com (Jack Hamilton) Subject: Re: Protest of New Compuserve-Unisys GIF Usage Tax Date: 3 Jan 1995 23:28:03 -0800 Organization: CRL Dialup Internet Access (415) 705-6060 [Login: guest] There have been many articles on this topic posted in the comp.infosystems. www.* groups, You should read all these articles yourself, but a reasonable summary, I think, is this: - Compuserve was charged by Unisys with a patent violation for the LZW compression algorithm used in GIFs. Compuserve had used the algorithm believing it was in the public domain, but in fact Unisys had applied for a patent. - Compuserve decided to license the technology rather than fight the patent. - Compuserve doesn't seem much happier about this than anyone else (except the people at Unisys, I guess). - Unisys clearly seems to be the villain here. - Compuserve has to pay royalties to Unisys. - The patent doesn't apply to GIF files themselves. Here's part of a message from Tim Oren, who claims to be a vice- President of Compuserve. CompuServe has not and is not asserting a proprietary interest in the GIF spec. Even if we wanted to, there are enough sharp attorneys here who could remind us that it has long been publicly disclosed with no patent filing or attempt to assert other rights. However, in developng GIF, we did use the LZW compression scheme. Unknown to us at the time, Unisys had filed for a patent on that algorithm, even though we found it in a public source. We were approached regarding the matter long after GIF had been widely released on CompuServe and to the market at large. Regardless of what you may think about software patents in general, or the tactic of waiting until substantial infringment has occured, we were in an infringing position and had no option to seek a license. Since we have a substantial base of developers who were not only creating clients to Compuserve, but had used GIF in good faith in their own products, we also needed to in some way protect their interests by developng a pass through license. The text of that license, or portions of it, are what's circulating around the nets. Because it has been taken out of context, many are taking it as an assertion, by CompuServe, of an intent to prosecute proprietary rights in GIF against all users, including developers of Web clients and other software. This is not the case. CompuServe has no intent of pursuing rights in GIF in such a fashion, and I am writing this with the knowledge and consent of our CEO. Unisys, of course, may follow whatever they see as their best interests in the matter. For better or worse, as a patent attorney can tell you, selective enforcement is allowed by the letter of the law. Tim Oren Vice President CompuServe and more from Mr Oren: Re GIF, I can talk about it, and if the impression being left is that we are trying to make big bucks, I definitely need to talk about it, because we've left the wrong impression. Here's the story, which you CAN repeat, WITH my name attached: GIF was originally developed at CompuServe by Steve Wilhite, who currently works for me. As part of it, he used with the LZW compression scheme, which had been openly published by Unisys engineer in a journal. A number of other developers picked up and used LZW as well. None of us knew that Unisys had filed for, and eventually received, a patent on the LZW scheme. I believe this is called a 'submarine' patent - it can surface and get you later. We were got. Unisys proposed an infringement suit, and we had no recourse but to settle. We are paying licensing fees in a manner which IS a nondisclosure item. One of the things we needed to be able to do is to 'pass through' a license embodying both LZW & GIF to those developers who create their own client programs to CompuServe, such as TAPCIS and Mac Nav, since they 'practice' LZW as well. The reason that GIF is included as a conditional in such licenses is that we can't pass through an unrestricted LZW license, and the reason there is money involved is that we in turn have to pay Unisys. If anyone is taking the impression that we are asserting proprietary rights in GIF additional to the LZW patent, that is wrong. Neither are we attempting to assist Unisys in enforcing their patent with respect to non-CompuServe environments, such as the Internet, though 'buying into' our license would be one way of Internet based vendors in avoiding possible action from Unisys. This is far more headache than it is worth, believe me, and we are actively engaged in looking at migration strategies that will get us and our customers off the hook. Our reputation has been damaged by being an unwitting partner to Unisys during those 7 years of encouraging proliferation, and we are not happy about it. (I'm sure Stallman - rms - could find a moral in here somewhere... ) ------------- Jack Hamilton jfh@crl.com KD6TTL '92 K75RTA co-moderator, sci.med.aids ------------------------------ From: jhallen@world.std.com (Joseph H Allen) Subject: Re: What is a T1 Line? Organization: The World Public Access UNIX, Brookline, MA Date: Wed, 4 Jan 1995 08:01:22 GMT In article , James Carlson wrote: > I'm afraid you'll have to re-read what I wrote. There is no such > thing as "cross-talk" at the *digital* level. One DS0 channel cannot > affect another within a T1 line; there just is no path for this to > happen. Any signal at all can be carried on a DS0, and the others > will be blissfully unaware that it exists. They are separated in > time. For a DS0 as defined as a TDM channel on a T1, this is true (excluding inter-symbol interference on a bad line). The original poster was concerned about a filter on a 56K copper pair, which prevented it from being used at any higher rate. In this case there is filter to prevent cross-talk between 56K copper pairs. An entire T1 can also go on a copper pair, but not with that filter. The fact that the line is a DS0 which eventually gets multiplexed onto a T1 also limits his bandwidth. If this is not the filter which the poster was referring to, then pardon me. >>> In fact Pulse Code Modulation (digital) without any error detection >>> has almost the same interference properties as FM radio. If two FM >>> stations are close, there will be noise. If they are really close, >>> you'll hear both stations at once and lots of noise. > The two are very different. PCM is a digital signal; if you can > recover it from the noise on the line, you'll get a "perfect" copy of > the data. Line hits will produce a decidedly non-analog type of > noise, with random data points being generated. To produce > traditional "cross-talk" effects, you'd have to do an arithmetic > average on the values of the data points between two lines. This is > highly unlikely to occur. > If you had two AMI lines next to each other, you'd need to have the > extraneous cross-talk signal exceed the pulse detection threshold of > the receivers in order to be able to detect *anything* at all. > Anything below this value would simply be invisible at the digital > level. If there are two PCM signals going at the same rate with no error detection, no sequence randomization, and out-of-band syncronization, and there is enough interference to mess with the detection threshold, you will here actual cross-talk. It will be very bad, and the original signal will also be almost completely munged. Yes, this is different from linear additive cross-talk, but it's still cross-talk. > FM, due to the nature of analog demodulation techniques, exhibits a > capture effect. If two signals are broadcast on the same frequency, > the "louder" signal will be heard to the exclusion of the "quieter" > signal. You won't hear both stations at once. If the received > amplitude of the two signals are varying with respect to each other, > then all sorts of interesting effects (depending on the type of > demodulation used) occur, but hearing both at once isn't one of the > options. This "capture" effect has nearly the same effect as two PCM signals on top of each other. The stronger one will get through if the weeker one doesn't mess with it too much. If they have the same signal levels, you'll have real cross-talk plus lots of noise (to the point where they are both nearly indistinguishable, same as PCM). This really happens, try it. >>> There's also a ~100KHz low-pass filter between the A/D converter and >>> the line to limit the edge rate of the digital pulses. Cross-talk is >>> more severe at higher frequencies, so limiting the unnecessary high- >>> frequencies caused by fast edges helps reduce cross-talk. > Any filter placed in the DS0 data path after quantization and before > multiplexing has no effect on the bandwidth of the signal that the > user of that DS0 sees. This has nothing to do with the poster's > original statements. It does, because the original poster was concerned about that bandwidth of the actual copper pair that came to his house. It's my understanding that an ISDN DS0 is 56K digital line on a copper pair between your house and the local office, not a shared T1 (although a multiplexer at the local office my put it on a T1). jhallen@world.std.com (192.74.137.5) Joseph H. Allen ------------------------------ From: writchie@gate.net Subject: Re: Britain-Japan Fiber Cable Date: 4 Jan 1995 06:31:23 GMT Reply-To: writchie@gate.net In , nagle@netcom.com (John Nagle) writes: > wrf@ecse.rpi.edu (Wm. Randolph U Franklin) writes: >> AT&T will build a cable from Britain to Japan for $1.2G. It'll be >> 17,000 miles long, 5Gbps, and carry 320,000 "voice and other messages". >> That looks like only 16Kbps per circuit (which looks low). The >> current longest cable is a 9,000 mile one from France to Singapore, >> completed a year ago. >> Fun math: That works out to a capital cost per circuit of only $3750. >> Assume that a phone call from Britain to Japan costs $2/minute. If >> all 320,000 channels were in continuous use, then the cable would be >> paid for in the first 31 hours. >> Alternatively, if we assumed that the cable is good for ten years, >> or 100,000 hours, then amortizing the capital cost would be three >> cents per hour, or $5e-4/minute. This is a factor of 4,000 less >> than the price of the call. > The numbers for the newer transantlatic cables look like that, > too. You really should be able to buy a full-time transatlantic > circuit for about $100/month, and at the rate cable is being laid, you > probably soon will. > Not having to acquire property rights is a big win. Fortunately, > the UN didn't think of this for the Law of the Sea conference. There is no question that the "cost" to the carriers of the international circuits is declining toward zero. That cost, however, has very little to do with what you pay for an int't private-line or switched service. An international circuit is two "half circuits" with the price at each end completely controlled by the carriers at each end, one or both of which is normally a monopoly PTT. Only US/Canada and US/UK circuits are priced at anything even reasonably related to cost. Until PTT's discover what price elasticity means, or they are forced by large private bypass users, tariffed rates are unlikely to reflect the low costs actually involved. The U.S. Model is informative. For interstate long distance the "costs" are $0.03 originating access (paid to LEC), $0.03 terminating access (paid to LEC), and $0.01 or less TOTAL operational cost for the IXC. Because the IXC has to pay the LEC's the $0.06, it has about $0.07 total cost resulting in a retail pricing on the order of $0.11 - $0.16. The IXC of course has to absorb credit risk on all of the true cost (including the LEC which gets its money in any case. The IXC also has marketing and other costs. Nevertheless the true cost of long distance is on the order of a penny a minute and that includes the switches. If access costs were reduced to the same magnitude as the long distance, the total retail price would be on the order of a nickel a minute. Intrastate is even worse. I actually pay less to call Ft. Lauderdale to London than I pay to call from Ft. Lauderdale to Miami. The fact is that most PTT's subsidize their large and politically powerful employee bases by maintaining the highest possible overall charges for international calling both in collection rates (charged to those in their country) and in accounting rates (charges to U.S. or other foreign carriers). The same true for private lines. In fact the "price" guideline for a private line is oftern based on 9000 minutes of switched usage, no relataion to cost. Wally Ritchie Ft. Lauderdale ------------------------------ From: writchie@gate.net Subject: Re: Finland Data Transmission Date: 4 Jan 1995 06:50:24 GMT Reply-To: writchie@gate.net In , jackp@telecomm.admin.ogi.edu (Jack Pestaner) writes: > We have been communicating to a site in Finland with autoranging 14.4k > modems. On a good day we can run at 9600, but typically at 2400. We > have tried AT&T, MCI, and IDB (all are direct digital connections > through our PBX), but all seem to be extremely variable. We use > NetBlazer modems, same model, on each end. > This is really expensive, and we want to move to a more reliable > service, as we expect to have longer hold times of three to five hours > a day. I checked on a 56k DDS, but cost was about $9K per month. > Are there any satellite solutions, or packet solutions that anybody > knows of? BTW, we also tried x.25 from Sprint, but service went down > often, and Sprint just has the WORST customer service for problem > solving. You might want to try different modems including some newer V.34's You might also investigate the nature of the analog loops at both your end and the Finland end. V32bis and V34 depend on effective cancellation of echo. Not all modem models are equally effective with circuits that have long delays. The types of echo cancellers and echo suppressors used on individual connections can also be a significant factor. Since you will be spending several $K per month, it should be worthwhile to investigate different modems and possibly some conditioning of the analog loops in Finland. How is your voice quality? Are you getting satellite circuits all the time?. What happens US/UK with the same modems? What happens Finland/UK. With the money your spending, the capital costs of the best modems money can buy are insignificant. Wally Ritchie Ft. Lauderdale, Florida ------------------------------ Subject: NANP 800 numbers from the UK Date: Wed, 4 Jan 1995 12:57:52 GMT From: Clive D.W. Feather All of a sudden, I can now dial 1-800 numbers from the UK. There is a few seconds of silence, and then an American female voice tells me that this call will *not* be free, but charged at standard direct-dial rates. If I don't want to pay, I should hang up now. Just for fun, I tried 1-800-MY-ANI-IS. It told me: "702 000 5555" ! Clive D.W. Feather | Santa Cruz Operation clive@sco.com | Croxley Centre Phone: +44 1923 813541 | Hatters Lane, Watford Fax: +44 1923 813811 | WD1 8YN, United Kingdom ------------------------------ From: rvb@iti.org (Raymond S. VanderBok) Subject: Cellular Billing Services Date: 4 Jan 95 13:02:09 GMT Organization: Industrial Technology Institute Are there service companies that provide custom billing for cellular service? I would like to be charged for service in a way different from what my cellular provider offers. Ray VanderBok Metalforming Manager NIST / Midwest Manufacturing Technology Center (313)769-4131 internet: rvb@iti.org ------------------------------ Date: Tue, 3 Jan 1995 22:35:58 EST From: Stan Schwartz Subject: Cell One NY/NJ Eliminates Daily Roam Charges It was buried in small print in the copy of their ad in Monday's {New York Newsday}, so I called customer service and verified it. As of 1/2/95, Cell One NY/NJ (00025) has FINALLY followed NYNEX Mobile's lead and eliminated the $3.00 daily "nag" roamer charge everywhere in North America. This applies to both NACN and Non-NACN cities (it was unclear in some cases whether some NACN cities charged the fee). At any rate, the only charges for roaming outside the NACN are 99 cents per minute airtime (still higher than NYNEX, for the most part). CellOne's customer service rep explained that some areas are 83 cents per minute instead of the 99, but they are few and far between - one should assume that it will be 99 and be pleasantly surprised if the bill is 16 cents less (per minute). A small celebration is in order! Stan ------------------------------ From: wiltzius@anduin.ocf.llnl.gov (David P Wiltzius) Subject: Summary: Telecom Texts Date: 4 Jan 1995 00:00:06 GMT Organization: Lawrence Livermore Nat'l Lab. I had several requests to post a summary so here goes. I haven't found a good textbook in telecom, but I think Newton's Telecom Dictionary is a very useful substitute. Because it is structured as a dictionary, one must piece together information from various entries, but I did pretty well on your test sentence. All the technical terms in your sentence were in Newton and they clearly pointed me toward the SONET entry, which is almost two pages long, and did a decent job of explaining your sentence, I think. I teach a course on information and communication technology (for industrial engineers); I use a collection of up-to-date articles on uses of telecom (Network World is one great source) and have the students use Newton to help them read these articles. I saw a book in Barnes and Noble called "Digital Telephony", Second Edition, by John Bellamy. Publisher is John Wiley, (c) 1991. IBSN 0-471-62056-4 After perusing the book, I came to the conclusion that it contains much of the information I am looking for (the same sort of thing you are looking for). The first chapter covers analog systems. The rest is digital. There is a chapter on SONET. I am still debating whether or not to get it (it was $75). I am interested but I could also spend $1000 on software engineering books (my occupation). Consider it requested. BTW, I bought some of the Telephony BASIC series. Haven't had a chance to look at them yet but they are THIN. I suspect they are VERY basic and not a good bargain. Happy Holidays, (Ed: I bought two of them (SONET and Wireless) months ago and I think they are worth their modest price. They are basic, as advertised.) McGraw-Hill, Delran, NJ 08075, publishes a series of reference books called Datapro. The series covers everything from how modems work, T-1 history, to vendor and product analysis. William Stallings has written several books on communications media and equipment. Titles slip my mind but I'm sure you should be able to find something by author search. -------------------Start off with "Digital Telephony" 2nd Ed. by John Bellamy ISBN 0-471-62056-4. He has a chapter on SONET that will give you a taste. Since the field is still emerging, many issues with SONET and SDH are still evolving. ------------------- RADIO SHACK CARRIES A BOOK CALLED "UNDERSTANDING TELEPHONE ELECTRONICS" WHICH EXPLAINS SUBJECTS FROM THE SIMPLE POTS TELEPHONE TO CENTRAL OFFICE EQUIPMENT. TELLABS, INC. PUTS OUT A TEXT BOOK COMPLETE WITH TESTS AT THE END OF EACH CHAPTER. HOPE THIS HELPS. IF YOU HEAR ABOUT OTHERS PLEASE LET ME KNOW. ------------------- You're welcome! I recently purchased an excellent telecom book from Artech House Inc.: "Service Management in Computing and Telecommunications." Artech specializes in telecom material. Their number is: 617-769-9750, call for a catalog. I've found them pleasant to do business with, but their prices, as with Computer Literacy, are full list (read: high). Speaking of price, if you're in the San Jose area, there is a large store near the corner of Hilsdale and Camden, across Hillsdale from Target, that buys close-out books from publishers. They sell most for under $5.00, and many for $3.00! Many books are college texts, and on some very good subjects. I was there this afternoon and picked up the "Artifial Inteligence Handbook ($3.00), Spencer Johnson's "Yes or No" ($3.00), "Voodoo Dos" ($8.00), Jimmy Carter's "An Outdoor Journal" ($3.00), Stanley Davis' "Managing Corporate Culture" ($2.00), and the "Pocket Guide to Phrasal Verbs" ($2.00). These are all hardbound editions. I didn't see any telecom material, but I have in the past. the place is huge, and I didn't look at everything. It's definately worth a visit if you're in the neighborhood, and you have the time. ------------------------------ End of TELECOM Digest V15 #5 ****************************