From editor@telecom-digest.org Sat Jul 24 17:49:44 2004 Received: (from ptownson@localhost) by massis.lcs.mit.edu (8.11.6p3/8.11.3) id i6OLnia18700; Sat, 24 Jul 2004 17:49:44 -0400 (EDT) Date: Sat, 24 Jul 2004 17:49:44 -0400 (EDT) From: editor@telecom-digest.org Message-Id: <200407242149.i6OLnia18700@massis.lcs.mit.edu> X-Authentication-Warning: massis.lcs.mit.edu: ptownson set sender to editor@telecom-digest.org using -f To: ptownson Approved: patsnewlist Subject: TELECOM Digest V23 #349 TELECOM Digest Sat, 24 Jul 2004 17:50:00 EDT Volume 23 : Issue 349 Inside This Issue: Editor: Patrick A. Townson More on 1970s British Numbering (Paul Coxwell) Maximum HLR/MSC/VLRs in a PLMN (qazmlp) Help - Please (News Feed) Phone Card Inquiry (Bill) Re: VOIP-Based IVR Broadcasting?? (Steven J Sobol) Re: Verizon as Local Telephone Provider?? (Steven J Sobol) Re: Senate Committee Guts VoIP Bill (anonfwd774@withheld on request) All contents here are copyrighted by Patrick Townson and the individual writers/correspondents. Articles may be used in other journals or newsgroups, provided the writer's name and the Digest are included in the fair use quote. By using -any name or email address- included herein for -any- reason other than responding to an article herein, you agree to pay a hundred dollars to the recipients of the email. =========================== Addresses herein are not to be added to any mailing list, nor to be sold or given away without explicit written consent. Chain letters, viruses, porn, spam, and miscellaneous junk are definitely unwelcome. We must fight spam for the same reason we fight crime: not because we are naive enough to believe that we will ever stamp it out, but because we do not want the kind of world that results when no one stands against crime. Geoffrey Welsh =========================== See the bottom of this issue for subscription and archive details and the name of our lawyer; other stuff of interest. ---------------------------------------------------------------------- From: Paul Coxwell Subject: More on 1970s British Numbering Date: Sat, 24 Jul 2004 15:08:38 +0100 There was a topic in the Digest recently about numbering in the U.K. during the 1978/79 period. I thought a little more background on this might be of interest. At that time, the British network had a combination of variable-length local numbers, STD (Subscriber Trunk Dialing) codes, and local routing codes. The British system had been very step-by-step oriented, with town and village offices having been arranged with number lengths dependent upon the number of subscribers served and the anticipated growth. Many small villages were served by a step UAX (Unit Automatic eXchange) and had 3-digit local numbers. These had generally been assigned starting in the 2xx range and extended upward as needed, although even into the early 1980s it was not uncommon to find tiny offices which had only 2xx and 3xx numbers, and maybe a few in the 4xx range. These village UAXs generally served only a very small area each. Larger exchanges in the 1970s had 4-, 5-, and 6-digit numbering, often with a mixture of number lengths within the same office. A typical small town might have started out with 4-digit numbers, then as needs grew extra number ranges were added which were 5- or 6-digits. It was very common to see towns with older 4-digit numbers in the 2xxx, 3xxx, and 4xxx ranges and newer 5-digit numbers in the 5xxxx, 6xxxx, and 7xxxx ranges. Over the years as demand grew, many towns changed the old 4-digit numbers to 5- or 6-digits by adding one or two digits to the front. For example, 2xxx and 3xxx numbers may have been converted to 72xxx and 73xxx, then after a suitable period new 5- or 6-digit numbers could be assigned to the 2 and 3 levels. The six largest urban areas -- London, Birmingham, Edinburgh, Glasgow, Liverpool, and Manchester -- used 7-digit local numbering which had been in place for many years. These are the only areas served by SxS switches which used directors,. all other step offices being non-director (i.e. each train of dial pulses stepped a switch directly, although to accommodate the numbering schemes many of the non-director exchanges made quite heavy use of digit-absorbing selectors). The six director areas had previously used a 3L-4N numbering format, although by the 1970s letters had been dropped and all-figure numbering adopted. (Note that British dials had assigned the letter "O" to the digit 0, leaving just "MN" on 6, so for example the old London number ACOrn 1234 was 220-1234, not 226-1234 as it would be in North America). Subscriber Trunk Dialing, the British equivalent of DDD, did not start to be implemented until the late 1950s, but local routing codes were already in use at that time to allow callers to reach nearby exchanges without going through an operator. These local routing codes were still heavily used in the 1970s. Many of the small village UAX offices mentioned above were linked to the nearest town as a dependent exchange, all calls in and out of the village being routed via that town (which became known as the GSC, or Group Switching Center). The typical arrangement put trunks to the GSC from a village UAX on the 9 level of the first selector, so subscribers on the UAX were told that they could dial the town as 9 plus the number. (This was also convenient in that it allowed easy routing of 999 emergency calls, which were handled by operators at the GSC, the village UAX offices being unmanned.) >From the GSC, trunks to each village UAX were generally a 2-digit routing code, often 8x, but sometimes 5x or some other combination if the 8 level had already been occupied. So subscribers in town could reach any of the village UAX lines with a 2-digit routing code plus the local 3-digit number. Subscribers on one village UAX could normally reach another UAX by dialing through the GSC, e.g. 98x plus the 3-digit number. Neighboring small towns were also fitted with direct-dial trunks in many areas, and quite often a single-digit routing code was assigned. Subscribers in town A might have been instructed to dial 6 plus the 4-digit number to reach town B, for example. In a few cases, there was sufficient traffic between two neighboring village UAXs to warrant direct trunks, and a similar arrangement was used (e.g. dial 7 plus the 3-digit number). If the trunk group got busied-out, those "in the know" could dial through the GSC with the appropriate 9+ routing, of course, as the incoming selector at GSC still had to allow access to the outgoing trunks for reaching the other dependent exchanges. When STD came along, it was decided to use 0 as the access prefix, although many people in Britain mistakenly consider the leading zero to be part of the area code itself due to way that numbers are written. Before STD, dialing 0 reached a local operator, just as in North America. London was allocated the shortest possible code, 1 (I'm omitting the zero STD prefix in all the following). The other five director cities with 7-digit numbering were allocated n1 codes, as follows: 21 Birmingham, 31 Edinburgh, 41 Glasgow, 51 Liverpool, 61 Manchester. It's notable that the codes assigned correspond to the appropriate first letter of the cities in question (e.g. B1 = 21 = Birmingham), but I don't believe that these particualr STD codes were ever listed as anything but all figures. (Note too that in the original plan 71, 81, and 91 were left spare, hence the use of 71 and 81 when London was split into two areas in the 1990s and the later assignment of 91 to the Newcastle area when it went to 7-digit numbering.) But back to the original STD plan ... Many people today often look at the STD lists and assume that the numbers were allocated completely at random, but they were not. All areas outside of the six cities listed above were assigned a 3-digit STD code, with letters in the first two places. For example, the town of Truro was assigned 872, listed originally as 0TR2. Letters were dropped from STD codes by the late 1960s, so that became just 0872 (now 01872, of course). Codes changed and assigned in the last 35 years or so used any conveniently spare numbers, but you can still see the original assignments in a large proportion of British area codes. By the way, the original plan allowed for area codes starting with zero (that's a zero AFTER the initial access prefix of zero, i.e. dialed as 00xx), but those codes were changed after letters were dropped, so the first digit of the area code itself became effectively an "n" digit, i.e. any digit 2 through 9. Once STD was implemented, subscribers could reach numbers in most towns by dialing the 0 access prefix, the STD code of 3-digits, followed by the local 4-, 5-, or 6-digit number. Calls to those tiny village UAX offices were treated exactly like a call to its parent GSC as far as the STD system was concerned. Direct dialing to such an exchange involved the use of both the STD code and a local routing code. Taking Truro that I mentioned as an example, there was a tiny UAX in the village of Zelah a couple of miles away. It's local routing from Truro used the code 54, so to call Zelah from elsewhere in the country the dialed sequence was 0 access prefix plus 872 code for the Truro GSC, plus 54 local routing, plus the 3-digit local Zelah number. The G.P.O. (General Post Office) who ran the telephone network at that time suggested the following preferred ways for writing numbers on stationery. The six director areas were to be written as all figures thus: 01-222 1234, 021-222 1234 etc. Other numbers were to be shown with both the exchange name and the STD code, e.g. Truro (0872) 2345 Subscribers on those small dependent exchanges were to write the local routing code as if it were part of the STD code, e.g. Zelah (0872-54) 234. The way in which local callers were instructed to use local routing codes rather than STD codes was perhaps confusing to many people. Another complication was that a neighboring GSC with its own STD code was often still a local call, and subscribers were told to dial a different local code, rather than the full STD code. For example, next door to 872 was another GSC with the STD code 326 (Falmouth). But because a local routing was already in place, callers from Truro were told not to dial 0326 but to use 91 plus the local number. (And a subscriber on a village UAX which homed on Truro would dial through using 991 plus the Falmouth number). Thus the listed STD code was always to be used when calling from a different part of the country, but anyone in the immediate local area would often be told to dial something quite different. So, to get back to the original question which prompted this, from an international perspective, dialing into the U.K. in the 1978/79 period would have been as follows: +44 1 plus 7 digits (London) +44 n1 plus 7 digits (five other major cities) +44 nxx plus 4, 5, or 6 digits (everywhere else) Regards, Paul Coxwell Norfolk, England. [TELECOM Digest Editor's Note: My thanks to Paul Coxwell for this very interesting and comprehensive report on 1970's British dialing. This report will be filed in our archives in the history section, for further rereference as needed. PAT] ------------------------------ From: qazmlp1209@rediffmail.com (qazmlp) Subject: Maximum HLR/MSC/VLRs in a PLMN Date: 24 Jul 2004 08:00:51 -0700 Organization: http://groups.google.com Does the GSM standard has a say about the maximum HLR/MSC/VLRs that can possibly exist in a PLMN network? What about the practical case? ------------------------------ From: mjs2032@rochester.rr.com Subject: Help - Please Date: Sat, 24 Jul 2004 02:42:09 -0400 Patrick, It seems that I don't understand the rules for posting to comp.dcom.telecom. I'm keenly interested in the E9-1-1 vs VoIP discussion and recently posted a response regarding that subject. Since it didn't make the cut I can only assume that either the content didn't pass the credibility test or that my anti-spam measures were too restrictive to meet the group requirements. Can you point me to the FAQs or otherwise advise me on what I need to do to join this important discussion. TIA Mike Sutter ENP - Ctek Inc Aka Mike_The_bike PO 141 Piffard, NY 14533-0141 USA +1.585.746.2032 mike@ctekproducts.com www.ctekproducts.com [TELECOM Digest Editor's Note: I have a couple of questions, Mike. Did you receive an auto-reply from me within a minute or two after you sent your message? If you did NOT receive an auto-ack then there is a good possibility your message never reached me OR it did get here and fell into my Spam Assassin file (auto-acks are not sent out on those.) If you did NOT get an auto-ack, because my incoming mail filters thought there was a strong possibility the message was spam then try resending it after attempting to clean it up a little. I do go through the spam bucket looking for obvious mistakes (for instance, a name I recognize as a regular poster here; a thread in progress with a 'Re:' subject line I've seen before, etc. When I now and then see those things, I issue a very short, simple manual ack back to the person to try to comfort them a little, since they took the time to compose the message and send it in. I am not like some moderators who just arrogantly toss out what they do not want to use. But there are times -- out of self defense more than anything else -- that I see a spam mail folder with 500 new items (only 500 new items? well, yeah cause I had previously checked the file just an hour or two earlier; if I don't check it for a full day, *then* you should see it) then I spend maybe 1-2 seconds reviewing the message sent by and subject lines for each item (a screen full -- 20 such lines -- gets all of *maybe 30 seconds between calling them up onto screen and then deleting them in clusters of the 20 on display* and moving the next 20 into view). It is EXTREMELY important to stick to the 'proper' subject header, have a 'reasonable' looking name, and a message length (according to the byte counter in Unix) of one to four or five K. That basically means do not use HTML (huge consumption byte-wise). If I see -- in this cursory review -- a Unix byte count of thirty or forty thousand bytes -- and Spam Assassin also thought it was spam, then I don't go further. I just bash them as fast as I can, twenty or thirty seconds per screen full, twenty messages per screen. The 'good' messages I find in this cursory review I pull out as I go through zapping the rest (almost all of them). Lisa Minter sits here usually each day two or three times and zaps spam also on the same formula. If you *did* get an auto-ack but the message still did not appear here then a couple things may have happened. First of all, I have my Spam Assassin set sort of low; I'd rather throw out a couple dozen spams/viruses rather than risk losing a good message. Ergo, a lot of spam which I would rather not answer at all, gets an auto-ack also. You got an auto-ack for this inquiry did you not? I found your inquiry in my regular mail, not the spam box. Using the same criteria as above, I scan through it all deleting the obvious spam and viruses. About 99.9 percent of what Spam Assassin catches is in fact spam. About 85 percent of what hits the real mailbox is also spam. Spammers are getting smarter, to say the least. Now and again, 'good' mail in the 'good' mailbox gets trashed by accident. I can recover/reconstruct most of that, or at least write to the person and ask their help in replacing the message. So did you or did you NOT get the initial auto-ack from me on the message about which you are inquiring? PAT] ------------------------------ From: Bill Subject: Phone Card Inquiry Date: Sat, 24 Jul 2004 13:50:53 +0200 Organization: Tiscali I'm looking for a prepaid phone card to call from the US to Europe. Without any payphone surcharges. What would you recommend? ------------------------------ From: Steven J Sobol Subject: Re: VOIP-Based IVR Broadcasting?? Date: Fri, 23 Jul 2004 23:28:51 -0500 bingoo wrote: > We are currently using an IVR application to dial numbers and play a > recorded message thru a dial-up telephone line. > We are looking for a VoIP solution by which our PC/software (connected > to DSL/T1 line) could dial a telephone number through a VoIP gateway > and, when connected, play the recorded message. Asterisk can do this. I'd use Asterisk, but there are probably a number of other IP-based PBXen that can do it just as easily. JustThe.net Internet & New Media Services, http://JustThe.net/ Steven J. Sobol, Geek In Charge / 888.480.4NET (4638) / sjsobol@JustThe.net PGP Key available from your friendly local key server (0xE3AE35ED) Apple Valley, California Nothing scares me anymore. I have three kids. ------------------------------ From: Steven J Sobol Subject: Re: Verizon as Local Telephone Provider?? Date: Fri, 23 Jul 2004 23:30:32 -0500 Carl Navarro wrote: > Our Verizon North residential bills don't come anywhere near that in > Ohio. Ohio seems to have the lowest, rock-bottom cheapest tarriffs of any US state. That point was driven home when I examined some of the differences between POTS pricing here in California and compared them to the pricing structure I was used to before I moved here from Cleveland. JustThe.net Internet & New Media Services, http://JustThe.net/ Steven J. Sobol, Geek In Charge / 888.480.4NET (4638) / sjsobol@JustThe.net PGP Key available from your friendly local key server (0xE3AE35ED) Apple Valley, California Nothing scares me anymore. I have three kids. ------------------------------ Date: Sat, 24 Jul 2004 01:17:49 -0400 From: anonfwd774@witheld at request Subject: Re: Senate Committee Guts VoIP Bill Pat, please withhold my e-mail address again. I guess there was one thing in my last message I should have explained a bit better -- the problem with any satellite-based service is that the equipment has to be able to see the satellite or satellites. Now by "see", I mean "clear line of sight." Ask any installer for Dish Network or DirecTV what happens when a branch with just a few leaves grows out into the path of the satellite dish. If a few leaves can stop a signal, imagine what a house wall or a basement wall will do. Most VoIP adapters are placed inside the house, and usually in places that don't see a lot of sunlight. One person I know has his in a utility closet in his basement, behind about 8-10 inches of poured concrete. I am quite sure that no satellite signal is going to penetrate there! I'm not really sure how handheld GPS receivers work and I've never owned one, but I'm guessing they don't work too well inside buildings! Perhaps someone who actually owns one could comment on that. Cell phone signals are inhibited by building walls (especially certain types of building materials), but not to the extent that satellite signals are. Even so, you've probably been in situations where you've had to move close to a window or step outside to use a cell phone. As for dismissing the notion that someone may want to snoop on a VoIP adapter, I'm sure that at one time people thought that no one would ever try to send a virus through e-mail, or try to induce people to go to a web site that would download a keystroke logger to their system. I really hope you are right, that it would not be worth anyone's time to try to hack into the box to obtain your location, but given the history of the Internet that is not the way I'd bet. ------------------------------ TELECOM Digest is an electronic journal devoted mostly but not exclusively to telecommunications topics. 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End of TELECOM Digest V23 #349 ******************************