From telecom-request@delta.eecs.nwu.edu Fri Sep 8 12:05:19 1995 by 1995 12:05:19 -0400 telecomlist-outbound; Fri, 8 Sep 1995 08:06:34 -0500 1995 08:06:32 -0500 To: telecom@eecs.nwu.edu TELECOM Digest Fri, 8 Sep 95 08:06:00 CDT Volume 15 : Issue 375 Inside This Issue: Editor: Patrick A. Townson Re: Area Code Crisis -- A Different Viewpoint (Fred R. Goldstein) Re: Area Code Crisis -- A Different Viewpoint (Wes Leatherock) Re: Area Code Crisis -- A Different Viewpoint (Sam Spens Clason) Re: Area Code Crisis -- A Different Viewpoint (Dik Winter) UC Berkeley Short Courses on Broadband and Wireless Comm (Harvey Stern) Variable Length Phone Numbers (Christian Weisgerber) Excel Telecommunications Cited For Slamming (DLD Digest via Mike Troutman) Re: Names For That Key Under the 9 (Mark Brader) Re: Names For That Key Under the 9 (Paul O'Nolan) Re: Names For That Key Under the 9 (John R. Covert) 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. Write and tell us how you qualify: * telecom-request@eecs.nwu.edu * The Digest is edited, published and compilation-copyrighted by Patrick Townson of Skokie, Illinois USA. You can reach us by postal mail, fax or phone at: 9457-D Niles Center Road Skokie, IL USA 60076 Phone: 500-677-1616 Fax: 708-329-0572 ** Article submission address only: telecom@eecs.nwu.edu ** Our archives are located at lcs.mit.edu and are available by using anonymous ftp. The archives can also be accessed using our email information service. 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A suggested donation of twenty dollars per year per reader is considered appropriate. See our address above. All opinions expressed herein are deemed to be those of the author. Any organizations listed are for identification purposes only and messages should not be considered any official expression by the organization. ---------------------------------------------------------------------- In article , dmcmahon@edlgu4.ericsson.se says... With regard to variable-length numbers and why they work in Europe and not in the USA or Canada ... >> [I don't know, never having been there, but I would expect that even >> in Germany where DDI numbers can have a variable length inward dialing >> suffix, the PBX would know still when to initiate an immediate >> connection because this no-prefix policy also applies to extension >> numbers (eg no ordinary extension numbers start with a 0). Can anyone >> in +49 confirm or deny this?] > Not from here, but there are two ways this can work: > 1) Get a speech path to the PBX and then dial your additional digits; > or > 2) Define either fixed (with additional analysis) or variable (with > timeout) length numbers in *ALL* exchanges where the PBX could be > called from, and that's a lot op places ... Neither is the reality. In practice, the way variable-length numbers works is based upon the trunk signalling (two l's, British spelling) method used in Europe, which is different from the trunk signaling (one l, American spelling) in the USA. The European networks (pre-SS7) used compelled signaling (such as MF/R2), in which each digit is sent on an open trunk down to the next, and ack'd at the far end. When the far end has enough digits, it sends the appropriate signal and the call goes ahead. This had some obvous round-trip-delay issues, but was plenty fast for the old steppers that dominated Europe. (This is a stepper-friendly scheme.) The USA, on the other hand, implemented toll dialing in crossbars, which have digit registers that store dialed digits. Thus the trunk isn't selected until a three-digit (or six-digit with NPA) prefix is dialed, and the dialed number is sent en-bloc once all seven or ten digits (plus the 1 in some cases, but that wasn't actually part of the number) are collected. In the American system, the originating switch needs to know how many digits will be there. IDDD time-outs, of course, are a hack that were added because of this incompatibility. With SS7 (or ISDN), digits can still be sent en-bloc or "compelled", as required. Fred R. Goldstein k1io fgoldstein@bbn.com Bolt Beranek & Newman Inc., Cambridge MA USA +1 617 873 3850 Opinions are mine alone; sharing requires permission. ------------------------------ martin@kurahaupo.gen.nz (Martin D Kealey) wrote: [ ... text deleted ... ] > What do you mean here? There is no NANP calling card format. I think you > are talking about LEC calling cards which (usually) mean NPA-NXX-XXXX YYYY > where YYYY is the PIN. It has nothing to do with carrier selection; in > fact, the call will be placed over the carrier that that particular phone is > presubscribed to (unless that carier doesn't accept LEC cars - unlikely). > Most IXC calling cards are not composed of a particular phone number, though > you can have the card number reflect your home number, since it is usually > possible to choose the number. This varies all over the place. Some IXCs typically *do* issue a calling card number that corresponds to your telephone number. I have had such cards from AT&T, MCI and Sprint, as well as my LEC, but also some which are non-conforming from the same IXCs. Calling cards are consistently used to make calls over carriers other than the one the calling phone is presubscribed to -- by dialing 10XXX+0+, or by dialing an 800 number. Sprint a year or two ago, and may still, have an arrangement to call using your Discover card. This is a different 800 number for this purpose, and you dial your Discover card number (16 digits) as your calling card number. Most carriers do accept calls on LEC cards or in that format, particularly carriers such as Oncor and other ones which charge excessive rates, since they have no other way to bill your call except through your LEC account. (Surely no one has an Oncor calling card[!].) Wes Leatherock wes.leatherock@hotelcal.com wes.leatherock@oubbs.telecom.uoknor.edu wes.leatherock@f2001.n147.z1.fidonet.org ------------------------------ In dmcmahon@edlgu4.ericsson.se (Denis McMahon) writes: > martin@kurahaupo.kurahaupo.gen.nz (Martin D Kealey) wrote: >> There is something to be said for having all national >> numbers of a uniform length to avoid other countries having >> to maintain digit-length tables, but this doesn't constrain >> length-variability of local numbers. > OK, but for every country any variable length national > numbers will invariably mean variable length international > ones as well. ie in the UK we have a mix of 10 and 11 digit > national numbers, and that means that +44 can be followed by > either 9 or 10 digits!! > This means that for calls to the UK, either the shorter > number length has to time out, or analysis has to be done at > the next digit - which is another ten lines of data to > maintain in every switch worldwide that supports > international dialing! In the good old days when calling grandma I'd dial 0175 (area code), wait for second dialtone and then dial her local number. Dialing 0175 actually connected me to her area code main exchange from where I then dialed her local number. This way my local or area code exchange needn't know anything about the numbering in 0175. Today there are some 300 AXE10 local and transport switches in Sweden. But there are only a few *gateway* switches. They'd be the only ones that need to deal with foreing numbering. Sam http://www.nada.kth.se/~sam, sam@nada.kth.se, +46 701234567 ------------------------------ Steve Cogorno writes: > The main problem with variable length phone numbers is NOT technical > as you have pointed out; it is difficult for humans to use. It is > very confusing to not know how many digits to expect. Suppose you > have a form that someone has filled out and there are only six digits. > Does this mean that the number is incomplete, or is it actually > correct? As variable length is/was just about the norm in Europe I can attest that it was not confusing. In the Netherlands the norm was that the first digit of the subscriber number told the number of digits. When expansion was needed some numbers got an additional first digit, again based on the original first number. So the (actual) number in Amsterdam 59121 was changed to 359121 and later to 6395121. The intercept is easy to understand: "The number has been changed, dial now first the digit 3 followed by the old number". What is the intercept after the grace period when you dial a number by its old area code in the US? The argument about forms is bogus. There are many cases where the number of figures is not fixed in something you can fill out in a form. When in the UK something fills in his car registration number as "V 5", would somebody wonder whether it was incomplete or actually correct? (Yes, that number does exist; I have seen it.) When somebody fills in his Dutch giro-account as 4832 does this mean the number is incomplete, or actually correct? (Again, that number does exist together with 5, 6 and 7 digit numbers. Probably also numbers with less digits.) Variable length phone numbers appear to be confusing to those not used to it; that does not mean it is generally confusing! dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924098 home: bovenover 215, 1025 jn amsterdam, nederland; e-mail: dik@cwi.nl ------------------------------ U.C. Berkeley Continuing Education in Engineering Announces 4 Short Courses on Broadband Communications, Wireless Networks SONET/ATM-BASED BROADBAND NETWORKS: Systems, Architectures and Designs (November 29-December1, 1995) It is widely accepted that future broadband networks will be based on the SONET (Synchronous Optical Network) standards and the ATM (Asynchronous transfer Mode) technique. This course is an in-depth examination of the fundamental concepts and the implementation issues for development of future high-speed networks. Topics include: Broadband ISDN Transfer Protocol, high speed computer/network interface (HiPPI), ATM switch architectures, ATM network congestion/flow control, VLSI designs in SONET/ATM networks. This course is intended for engineers who are currently active or anticipate future involvement in this field. Lecturer: H. Jonathan Chao, Ph.D., Associate Professor, Brooklyn Polytechnic University. Dr. Chao holds more than a dozen patents and has authored over 40 technical publications in the areas of ATM switches, high-speed computer communications, and congestion/flow control in ATM networks. MODERN TELECOMMUNICATIONS: Wide Area Networks, Personal Communication Systems, Network Management and Control, and Multimedia Applications (November 2-3, 1995) This course is designed as a gentle but comprehensive overview of telecommunications including current status and future directions. This course traces the evolution of telecommunications, starting from its voice roots and progressing through local, metropolitan, and wide area networks, narrowband ISDN, asynchronous transfer mode, broadband ISDN, satellite systems, optical communications, cellular radio, personal communication systems, all-optical networks, and multimedia services. Lecturer: Anthony S. Acampora, Ph.D., Professor, Electrical Engineering, Columbia University. He is Director, Center for Telecommunications Research. He became a professor following a 20 year career at AT&T Bell Laboratories, is an IEEE Fellow, and is a former member of the IEEE Communications Society Board of Governors. NETWORKS FOR DIGITAL WIRELESS ACCESS: Cellular, Voice, Data, Packet, and Personal Communication Systems (November 8-10, 1995) This comprehensive course is focused on the principles, technologies, system architectures, standards, and market forces driving wireless access. At the core of this course are the cellular/microcellular/ frequency reuse concepts needed to enable adequate wireless access capacity for Personal Communication Services (PCS). Presented are both the physical-level issues associated with wireless access and the network-level issues arising from the inherent mobility of the subscriber. Standards are fully treated including GSM (TDMA), IS-54 (North American TDMA), IS-95 (CDMA), CT2, DCT 900/CT3, IEEE 802.11, DCS 1800, and Iridium. Emerging concepts for wireless ATM are also developed. This course is intended for engineers who are currently active or anticipate future involvement in this field. Lecturer: Anthony S. Acampora, Ph.D., Professor, Electrical Engineering, Columbia University. He is Director, Center for Telecommunications Research. He became a professor following a 20 year career at AT&T Bell Laboratories, is an IEEE Fellow, and is a former member of the IEEE Communications Society Board of Governors. ATM DATA COMMUNICATIONS NETWORKS: Internetworking, Signaling and Network Management (November 27-28, 1995) This short course examines the key issues involved in designing and implementing high-performance local and wide area networks. Topics include: technology drivers, data protocols, signaling, network management, internetworking and applications. Lecturer: William E. Stephens, Ph.D., is the Head of the Wireless and ATM Networking Group at the David Sarnoff Research Center. Prior to this he was Director, High-Speed Switching and Storage Technology Group, Applied Research, Bellcore. Dr. Stephens has over 40 publications and one patent in the field of optical communications. He has served on several technical program committees, including IEEE GLOBECOM and the IEEE Electronic Components Technology Conference, and has served as Guest Editor for the IEEE Journal on Selected Areas in Communications. For more information (complete course descriptions, outlines, instructor bios, etc.) send your postal address or fax to: Harvey Stern or Loretta Lindley U.C. Berkeley Extension/Southbay 800 El Camino Real Ste. 150 Menlo Park, CA 94025 Tel: (415) 323-8141 Fax: (415) 323-1438 email: southbay@garnet.berkeley.edu ------------------------------ Recently, comp.dcom.telecom has seen some talk on the viability of variable length phone numbers within a country (or any specific network, for that matter). Many posters, especially those from North America, insist on their belief that phone numbers have to be of constant length, otherwise one must have timeouts etc. First, let me state that I see *no reason whatsoever* why there can't be variable length phone numbers or why a switch would have to know the total length of the number. If you think there is a need for such restrictions, please explain why you think so. Your reasons are not obvious. I would also like to point out that in Germany, where I live, telephone numbers vary in length, in fact my voice number is +49.621.5870460 and my modem number is +49.621.583214, area codes vary in length (2..5 digits), we have DID numbers of different lengths, and all of this without any kludges like second dial tones, timeouts, etc. Claiming that this is impossible is ridiculous in face of the facts. What is a phone number? For the most part, a phone number is a *route* through the network. The last few digits are a unique ID that maps onto ·_ a particular line in the destination switch. (Whether the destination switch is a telco CO or a PBX does not matter.) What must a switch do during call set-up? It receives dialing information (single or multiple digits) from an inbound trunk (or from the line card, if it is the caller's switch), and, after collecting enough of these, selects an outbound trunk. Further dialing info it receives is passed on to the switch on the outbound trunk. Note that no trunk line has to be actually connected yet. The destination switch collects dialing info until a line that it serves is identified, then it initiates a ring signal. Information about this is passed back the chain of switches to the caller's switch which locally feeds a "remote is ringing" signal. When the called line answers, again information is passed back to the caller's switch, and now the speech circuit is actually activated along the switch chain. Of course the above is somewhat simplified, but it is the principle a call set-up works by. In the ISDN age, the switches communicate using SS7 or, in the case of ISDN BR and PRIs, both of which can be used to connect PBXes by the way, the D channel protocol preferred in your part of the world. This system works with SS7/ISDN. It also worked with the prior German phone technology, purely electro-mechanical switches. (That's relays, levers, etc. No transistorized technology whatsoever.) With that technology speech circuits were connected through to the next switch already during dialing, though. So, you want to give me a call? Okay, you dial +49 or within Germany 0. Now you're on the long distance level of the German Telekom network. You dial selects - <6> South western Germany. - 6<2> The Ludwigshafen/Mannheim area. - 62<1> The cities of Ludwigshafen and Mannheim themselves. - 621 <5> Ludwigshafen. - 621 5<8> The particular part of Ludwigshafen I live in. - 621 58<70460> That's my line. My phone is ringing! (Actually, the final 0 helps selecting a particular device on my ISDN line.) When I answer the phone, the call circuit will be established and voila! Easy, isn't it? Christian 'naddy' Weisgerber naddy@mips.pfalz.de See another pointless homepage at . ------------------------------ WASHINGTON, D.C. -- EXCEL TELECOMMUNICATIONS, INC. Is apparently liable for a forfeiture of $80,000 in slamming cases (switching a person's primary long distance carrier without their prior authorization). Common Carrier Action by the F.C.C. August 18 by NAL (Notice of Apparent Liability) (DA 95-1833). According to Anna M. Gomez, a spokesperson for the F.C.C., "apparently solid facts", have been brought to the F.C.C.'s attention concerning two specific slamming incidents. The complainants Mr. Bruce Adelman of Los Angeles, CA and Mrs. Robert J. Blake of Altadena, CA both had their long distance services wrongfully switched to Excel through the use of both forged signatures AND forged social security numbers. To see if there was a trend here, Discount Long Distance Digest also checked with the California State Public Utilities Commission to investigate whether Excel has slamming complaints pending against them on a state level. According to Marko Valente, Manager of Consumer Affairs at the CPUC, Excel has had approximately 10 informal slamming complaints (24 total) made against them by California residents during 1995. None have resulted in more serious 'formal' complaints. The figures seem to be at, or even below, the average level for a long distance provider. Chris Dance, VP of Legal Affairs at Excel stated, "It is the first penalty ever implied upon Excel by the F.C.C. The 'slams' in question were committed by certain independent contractors of Excel, and Excel intends to pursue and prosecute the independent sales representatives involved in order to recover these amounts". Dance also stated that Excel will file a petition for reconsideration with the F.C.C. within the week. Excel currently has approximately 300,000 independent sales representatives. [Ed: Uh ... make that 299,998 independent sales agents!] ------------------------------ > Anyone add to this list? Square. > (2) what is the derivation for the term "pound key", since the symbol on > telephones bears no similarity to that used for British currency. One use for the symbol is pounds weight, as in non-metric measure. In my experience (in Canada, with heavy exposure to US writing) this is much rarer than its use as a number sign. > I would hazard to guess that the answer to this derives from confusion > over the standard computer character set used in the UK, which differs > from ASCII by only one character... No; either that's a coincidence or else someone thought it was a good idea to make the substitution in the position of a symbol sometimes called by a similar name. The use for pounds weight is much older than ASCII. > [TELECOM Digest Editor's Note: We covered this in excruciating, exhaustive > detail here once before ...] Yes, and all of it anecdotal. I say let it die, unless this time we can actually hear from someone with *evidence*. Mark Brader msb@sq.com SoftQuad Inc., Toronto ------------------------------ > [TELECOM Digest Editor's Note: We covered this in excruciating, exhaustive > detail here once before, but I don't fault you if you can't remember it, > since it was several years ago. Volume 8, issue 190 of this Digest, dated > December 1, 1988 was devoted entirely to theories about the naming of #. > This followed an inquiry just like yours in mid-November of that year, and > a number of reply messages which ran from then through the end of the month > and culminated in the special issue of December 1. > And no, I am not like Ann Slanders or her sister Scabby Van Buren. I do > not re-run letters I got years ago on days when the mail is a little light, > which it never is around here anyway. Mr. Kealey did write and ask the > question just recently. Anyone interested in 'How the Octothorpe Got its > Name' as that issue was called, can pull it from the Archives. Look in the > dusty old volume 8 stuff. Maybe I *should* re-run it. Opinions? PAT] Rerun it! [TELECOM Digest Editor's Note: Okay I will, following this issue of the Digest. Thus far the mail responses are running heavily in favor of seeing it again. PAT] ------------------------------ martin@kurahaupo.gen.nz (Martin D Kealey) asks: > what is the derivation for the term "pound key", since the symbol on > telephones bears no similarity to that used for British currency. Neither does the name for the key. "#" is the "pound sign" commonly used in Civil and Mechanical Engineering to represent pounds of weight or force. john ------------------------------ End of TELECOM Digest V15 #375 ******************************