TELECOM Digest Tue, 10 Jan 95 04:29:00 CST Volume 15 : Issue 20 Inside This Issue: Editor: Patrick A. Townson Re: Noise Introduced by Bit-Robbing? (Tim Gorman) Re: Noise Introduced by Bit-Robbing? (Wally Ritchie) Re: Christmas Greetings From AT&T (Sam Spens Clason) Re: ISDN Over Wireless (John Lundgren) Re: Erlang Capacity (Phil Ritter) Re: Need an EBCDIC Spec - ebcdic.rq [1/1] (John O'Keefe) Re: NANP 800 Numbers From the UK (Judith Oppenheimer) Re: Sprint and Calls Within Your Service Area (Al Cohan) Re: Procedure for Obtaining a 10XXX Code (Mark Fraser) Re: Procedure for Obtaining a 10XXX Code (Joe George) Re: More CO Codes For Each NPA - Any Telcos Take Advantage? (David Leibold) Re: Flat Rate Cellular Phone Service (jhupf@nando.net) Re: MANs in USA (Fred R. Goldstein) Re: Cellular NAM and ESN (Eric Tholome) 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: 708-329-0571 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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Any organizations listed are for identification purposes only and messages should not be considered any official expression by the organization. ---------------------------------------------------------------------- Date: Mon, 9 Jan 1995 20:55:49 -0500 From: Tim Gorman Subject: Re: Noise Introduced by Bit-Robbing? whs70@cc.bellcore.com (sohl,william h) writes in TELECOM Digest V15 #11: > In article , wrote: >> In , naddy@mips.pfalz.de (Christian Weisgerber) >> writes: >>> What kind of noise/distortion does American-style bit-robbing cause to >>> voice band signals transmitted through PCM channels? >> In the U.S., most intermachine trunks are common channel direct >> connections so only the robbed bit at each end of the IC/EC connection >> introduces the robbed bit (as well as ny non CCS systems in the EC). > Today, most end-to-end voice connections do not include any trunking > which uses robbed bit signalling. The great majority of local > trunking, especially in metro areas, has all been converted to CCS. > One way to determine the probability of what type of local trunking is > in your area is if caller ID is available. If you can have caller ID, > then the local trunking is using CCS and thus no robbed bit signaling > is involved at that end of any connection. This is probably a little misleading. While the robbed bit signaling was for use in per-trunk signaling for passing supervision information, merely converting to SS7 signaling (i.e. making caller id available) doesn't automatically make the robbed bits available. This also requires conversion to B8ZS/ESF signaling. I think you will find lots of places that have converted to SS7 still have the older AMI/SF facilities in place thus limiting circuit bandwidth to 56kb. Tim Gorman Southwestern Bell Tel Co tg6124@ping.com ------------------------------ From: writchie@gate.net Subject: Re: Noise Introduced by Bit-Robbing? Date: 10 Jan 1995 09:11:06 GMT Reply-To: writchie@gate.net In , duggan@cc.gatech.edu (Rick Duggan) writes: > In article , sohl,william h com> wrote: >> In article , Matthew P. Downs >> wrote: >>> Unless you use ISDN, you are using robbed-bit signalling between your >>> premise and the Central Office. Unless like a previous poster had >>> stated, the robbed bits only become important during call set-up and >>> tear-down. Ie. going on-hook and off-hook. Otherwise the robbed bits >>> will be 1's. > In a sense, the robbed bits are only important during call set-up and > tear-down. However, since (a) we don't know when set-up/tear-down > occurs and (b) we don't have control over where our PCM data goes, we > can't use those bits at all. Which gets back to why it's called > robbed-bit signaling in the first place. Their presence still affects > the bandwidth that can be obtained. It doesn't matter if the robbed bit is steady 0, steady 1, or whatever. The robbed bit steals the LSB of the encoded PCM word and introduces an error. The effect, though small, is present NOT JUST during call set up and tear down but wherever Robbed bit signalling is used. Furthermore, the number of individual signalling links will effect the total noise introduced. This is because the robbed bits occur every 6 frames and the multiframes of the Local Loop A, EC/IC Trunk A, IC/ED Trunk B, and Local Loop B are NOT aligned. For MOST (that is more than 50% and much more likely 90%) of all long distance connections in the US there will be more than 2 and as many 6 Robbed Bit links involved. The impact on the S/N ratio can range from 2 to more than 10 db. Wally Ritchie Ft. Lauderdale, Florida ------------------------------ From: d92-sam@dront.nada.kth.se (Sam Spens Clason) Subject: Re: Christmas Greetings From AT&T Date: 9 Jan 1995 19:29:57 GMT In Ari.Wuolle@hut.fi (Ari Wuolle) writes: >> Well, we'll find out how this works over here in a couple of years. >> Austria just joined the EU, and the EU has decreed the end of telecom >> monopolies by the end of 1996 (or is it 1998)? We will all be faced >> with the same problems and privileges then. Ah, but I just read that the Comission has given in to pressure from the former monopolies in the new member states Sweden and Finland. It was a very small article in todays paper that said that there would be no EU-laws but rather "recommendations" regarding telco competition issued by the commission. Can anyone shed some light on the details of this? > Finland also just joined EU, but our local and long distance monopolies > ended already 1st January 1994. International call traffic was deregulated > fully in summer 1994. Sweden got deregulated mid 93. In theory Sweden is more deregulated than Britain, second only to NZ. However there is still a de facto monopoly since there is only one operator that offers local calls -- telia (former dept. of telecom). That might change when Singapore Telecom gets their Stockholm operation up and running (they just bought a cable company with 1/4M subscribing households). Only nobody knows when that is going to be. And since there is only one competitor on LD and int'l calls the prizes aren't really as low as in Finland during office hours. > You can always choose different carrier by dialling its carrier code > before telephone number you are calling to. Telcom Finland is 101, > Telivo 1041 and Kaukoverkko Ysi 109. > Currently you cannot choose default international carrier - you must > use correct international access code, which are now carrier > dependent, 990 for Telecom Finland, 994 for Telivo and 999 for Finnet. > (Old international access code was 990.) Hopefully this will change in > 1996 when new 00 international access code will take over old ones. We too have carrier dependent access codes. 007 is Tele2 and 009 (the old access code) is Telia. To call me using Tele2 would be 007 08 661 3882. One cannot use Tele2 without being a subscriber, though it costs nothing and is a pure formality this halts competition a lot. It's hard to understand that people can't be bothered making *one* toll free call and sign *one* paper to get 5-10% off their LD and international calls. Regards, Sam Spens Clason home: 08-661 3882 everywhere: 070-1234567 ------------------------------ From: jlundgre@kn.PacBell.COM (John Lundgren) Subject: Re: ISDN Over Wireless Date: 9 Jan 1995 19:02:30 GMT Organization: Pacific Bell Knowledge Network Jared Enzler (jenzler@olympus.net) wrote: > I live in an area where the telephone co. shows no interest in > offering ISDN. But the area is well covered by cellular phone > systems. > Questions: There appear to be several varieties of digital cellular on > the way. Do any of these have the potential to offer ISDN? Which > ones? What sort of technical or other barriers are there to wireless > ISDN? ISDN is 144,000 bits per second, and that would take an awful lot of bandwidth to transmit over radio. I don't think CDPD or whatever they call digital cellular has channels that are anywhere near that wide. Find out if the phone company has a newer 5ESS switch. If not then they can't offer ISDN. THe central office may have a 5ESS switch, but the distance to your phone is too far. They can get around that by putting in a T1 line that would serve up to 24 subscribers in the neighborhood, but it would cost money, and some telcos just don't want to do that. John Lundgren - Elec Tech - Info Tech Svcs Rancho Santiago Community College District 17th St. at Bristol \ Santa Ana, CA 92706 jlundgre@pop.rancho.cc.ca.us\jlundgr@eis.calstate.edu ------------------------------ From: pritter@nit.AirTouch.COM (Phil Ritter) Subject: Re: Erlang Capacity Organization: AirTouch Cellular, Los Angeles Date: Mon, 9 Jan 1995 15:00:15 GMT In article Tim Gorman writes: > ERU.ERUDYG@memo4.ericsson.se writes in TELECOM Digest V15 #2: >> I am looking for information about Erlang Capacity Calculations for >> land line based telecom networks. My main question is this: >> In cellular, typical system design is according to Erlang B or Erlang >> C traffic tables, and designed for 2% blocking (.02 G.O.S., Grade Of >> Service). [stuff deleted] > Again, it has been a while but I thought Erlang C was not used for > figuring blockage to offered load on a trunk group but instead for > figuring holding time in queue while waiting for answer. Are you sure > you use Erlang C in trunk blocking or do I have my tables mixed up :- ) ? Indeed, Erlang-B is used to predict blocking when a blocked-call is discarded and Erlang-C is used when a blocked call is queued to wait for a free trunk. The ability of a cellular phone to produce a minimum effort redial (the user just has to press send again -- many phones will do this automatically) mimics queueing so well that Erlang-C becomes a better predictor of blocking. Phil Ritter pritter@la.airtouch.com ------------------------------ From: jgo@cci.com (John O'Keefe) Subject: Re: Need an EBCDIC Spec - ebcdic.rq [1/1] Organization: Northern Telecom, Network Application Systems Date: Mon, 9 Jan 1995 14:46:08 GMT In article , Brent E. Boyko wrote: > In article is written: >> I'm working on a project which requires conversion of EBCDIC to >> ASCII and visa-versa. Does anyone know where I can find: >> 1) a spec for the EBCDIC character set, >> 2) source code which performs such translations and/or >> 3) a library which performs these translations. > The Unix utility "dd" can be used to convert USASCII to EBCDIC and > vice versa. For example, the following command would read the ascii > file "text.file" and write it in 80-column EBCDIC format to mag tape > drive 0, using 8000 byte blocks: > dd if=text.file of=/dev/rmt0 obs=8000 cbs=80 conv=ebcdic > Source code is available as part of the GNU fileutils package. Get the > file fileutils-3.12.tar.gz from the GNU ftp archive at prep.ai.mit.edu, > gatekeeper.dec.com, or ftp.uu.net. A word of caution with the block translation approach with EBCDIC to ASCII. If there are any packed-decimal fields in the record, it will translate garbage. You need a utility that does field-by-field translations for these fields. Highest Regards, John O'Keefe jgo@cci.com ------------------------------ From: Judith Oppenheimer Date: Mon, 9 Jan 1995 08:12:32 -0500 Subject: Re: NANP 800 Numbers From the UK A week or two back, a query was posted by Jan Joris re free phone calls. > What's happening? Is the Dutch PTT blocking calls that could be perfectly > well completed? Or do the Britsh have a special agreement with the Americans > that not valid in the Netherlands? Who knows more? I'm told that most of the decisions on whether to complete calls or not are based on discussions at the Freephone Fourm. This is a group of (mostly marketing) people who provide service around the world. The Freephone fourm has recently approved a bilateral agreement called "plus freephone". To dial a freephone number in an other country, you dial: + (the international access code, 00 is europe 011 in US) CC (the country code of the country the number belongs) XXX...XXX (the freephone number.) So 00-1-800-xxx-xxxx is actually + followed by country code 1 followed by the number. If the country has signed up for bilateral agreement, as soon as it sees 00, it routes to an international gateway function, then it sees 1 and validates that as a valid country code (USA) and then looks at the 800 and recognizes that as "suppress billing" and completes the call. Otherwise if they don't support this, they recognize 800 as free and rejects the call after the fourth digit. All switches must be able to read and route based on the first four digits. After Dec 31, 1996 they must be able to read and route based on the first seven digits. So it is quite normal for the call the be rejected after four digits right now, and seven later. (Dec 31, 1996 is called Time-T after which all switches will accept phone numbers up to 15 digits (instead of 12) and route on seven digits instead of four). Judith Oppenheimer ------------------------------ From: ac554@lafn.org (Al Cohan) Subject: Re: Sprint and Calls Within Your Service Area Reply-To: ac554@lafn.org (Al Cohan) Organization: The Los Angeles Free-Net Date: Tue, 10 Jan 1995 07:32:57 GMT In a previous article, henderson@mln.com (Javier Henderson) says: > I just got off the phone with Sprint's customer service. Their special > offer of one cent per minute for calls within your service area applies > to all of Sprint customers, regarldess of what calling plan you're on. > You need to dial 10333, but considering the savings, I don't mind. The úÿ > charge is the same regardless of mileage. > The offer will expire on Feb 28, 1995. > I'm not associated with Sprint, other than as a mostly satisfied customer. > The above applies to residential lines in Southern California. Other areas > within California may have the same deal, you'd better check. Most of what you say is *not* true. In response to several of my telecom clients, I called Sprint (800 877-4040) on several occasions. I was misinformed 8 out of 10 calls. No, I am not kidding. The first few calls I was told just dialing 10333 is all that I had to do. Then I was told "I'm sorry, our promotion is for Sprint Customers Only"! In short, they didn't want my business. I never heard of a "promotion" for existing customers ... Finally I got a hold of a Sr. Supervisor after two days. The upshot of what I was told is that you have to subscribe and be validated in their switch or otherwise the LEC will get the billing at standard (15c per minute) rates. Also, the rate outside of the LATA 730 is standard rates and does not carry the 1 cent per minute charge ... it only applies to residential customers only, but they are working on a business customer plan to roll out shortly. After my account was validated, I called Sprint two more times, got the name of the telemarketer, confirmation code and was lied to again ... I'd hate to be at the end of customer service when all of these 1 cent calls come in at 15 cents and appear on the LEC billing! I suggest you call Sprint three times and see if you get three answers, then verify with a supervisor. I did this twice and both times was told misleading information. I sure hope that they get this straightened out because an organization the size of Sprint will have tremendous problems unraveling this misinformation. Most of there telemarkets are *not* located in California. Good Luck. Please e-mail me with your results. ------------------------------ From: mfraser@vanbc.wimsey.com (Mark Fraser) Subject: Re: Procedure for Obtaining a 10XXX Code Date: 10 Jan 1995 04:41:31 GMT Organization: Wimsey Information Services And while we're at it, are there any 10XXX[X] codes assigned in Canada? Mexico? Since at least Canada is part of the historical numbering plan, and since we have begun to experience the joys of competitive toll calling, and since the "dominant" carriers must give equal access to other carriers when a subscriber dials a leading "1", it seems sensible that these carriers might just want to have 10XXXX. Anyone comment? Mark ------------------------------ Date: Tue, 10 Jan 1995 09:45:54 GMT From: Joe George Subject: Re: Procedure for Obtaining a 10XXX Code > [TELECOM Digest Editor's Note: Is this any stranger than a newspaper > having a three digit number of its own, ie 311, like that newspaper > in, where is it, Georgia? PAT] Yup, in Atlanta the local rag (also known as the {Atlanta Journal- Constitution} bought 511 from BellSouth for a classified search service (and other services). It's 50 cents a call but you get three free calls per month. BellSouth also sold out on 711 to a job search company, but I don't know much about it. Joe George (jgeorge@nbi.com, jgeorge@crl.com) (Please don't use 'jgeorge@twiglet.nbi.com' anymore.) ------------------------------ From: aa070@torfree.net (David Leibold) Subject: Re: More CO Codes For Each NPA - Any Telcos Take Advantage? Organization: Toronto FreeNet Date: Tue, 10 Jan 1995 07:18:14 GMT A correction and a clarification on my article on NXXes in NPAs (originally posted from gvc.com instead of here) ... 1) While St. John's is the capital of the Canadian province of Newfoundland, there is the oft-confused Saint John, New Brunswick which I was a bit too hasty to proclaim as a provincial capital. That privilege, I believe, actually goes to another of the New Brunswick cities. 2) There have been N0/1X exchanges in some area codes already, of course (212, 213, 312, etc). The focus of the posting, to clarify, was those area codes that did *not* have N0/1X CO codes before now, such as NPA 506 or 807 where there aren't that many NXX in service. In other words, will telcos in those cases assign N0/1X codes because they are now able to, rather than because they have to? David Leibold aa070@freenet.toronto.on.ca ------------------------------ From: Jhupf Subject: Re: Flat Rate Cellular Phone Service Date: Mon, 9 Jan 1995 13:09:07 EST Organization: News & Observer Public Access On Wed, 4 Jan 1995, Andrew Laurence wrote: > Jhupf writes: >> Cellular One of Triangle here in the Triangle in North Carolina offers >> full local access on weekends for $10 a month. We were considering >> going for it until we realized we had an accmulation of more than 575 >> minutes of local calling credit we haven't been able to use during the >> past 14 months. > Are you saying that Cellular One lets you carry unused minutes from > your allowance over to future months? GTE Mobilnet here in the San > Francisco Bay Area has a "use 'em or lose 'em" policy. Sorry for any misunderstanding; the 60 minutes a month I get with my calling plan are on a "use 'em or lose 'em" basis. What I have accumulated are the balance of the bonus time I got when I initially signed on to CellularOne plus what I got when I renewed my service with them after the first year. I was surprised when I got my bill to see that they carried the balance of the first years bonus forward and added to the new bonus! The balance is available to use after I have gone through my monthly allocation under the plan I have. ------------------------------ From: fgoldstein@bbn.com (Fred R. Goldstein) Subject: Re: MANs in USA Date: Mon, 9 Jan 1995 12:09:10 GMT Organization: Bolt Beranek & Newman Inc. In article <3ej414$d7@galaxy.uci.agh.edu.pl> rumian@uci.agh.edu.pl writes: > I need some help in getting info about Metropolitan Area Networks > in USA. You may note that none of the early replies came from the USA, which is all you asked for! This is because there are essentially no MANs in the USA. They aren't a major commercial force. The telephone companies cannot offer 802.6 MANs because 802.6 requires that the telephone company own the bridge at the customer site, but US telephone companies are prohibited from owning customer premise equipment. Some US telephone comanies offer SMDS, a connectionless data service which was originally run over 802.6 facilities. But most SMDS nowadays is run over HDLC point-to-point circuits. Some companies own private MANs, often using FDDI which may be using "dark fiber" leased from a telephone company, and in a few cases telephone companies offer FDDI MAN services. But none of these amount to a lot of business. The major high-bandwidth carrier services are DS3 leased lines and, coming Real Soon Now, ATM. Fred R. Goldstein k1io fgoldstein@bbn.com Bolt Beranek & Newman Inc., Cambridge MA USA +1 617 873 3850 ------------------------------ From: tholome@dialup.francenet.fr (Eric Tholome) Subject: Re: Cellular NAM and ESN Date: Mon, 09 Jan 1995 21:35:44 +0200 In article , gsegalli@ic1d.harris.com (Greg Segallis) wrote: > Can two cellular phones be programmed to the same NAM, while their > ESN's are different, so that either phone can be used on one number? > Assume only one phone can be on at a time (e.g. I have a car phone I > use while on the road and a portable I use when I'm away from my car). > Does the cellular carrier use the NAM to connect calls or the ESN, or > both? If the ESN must be the same, can I alter the one to match the > other? This would not be done to steal anyone else's service, just to > allow me the convenience of using both my phones as the situation > requires/allows. What are the legal issues in doing this? To which Pat replied that it would be a very bad idea to do it, leaving the door open for theft of airtime (well, Pat did say many other things, but let me get to my point :-) GSM solves the problem of two phones (or more) for one line in a very nice way: the subscriber identity is totally separated from the terminal: it is located on a SIM (Subscriber Identity Module) card. This way, you can have as many phones as you mant and still have one single phone number: simply plug your card in whatever phone you intend to use! You may even plug your card in somebody else's phone, or in a rented car phone, for instance. Very convenient, indeed. Of course, the terminal still has an identity, and, if reported stolen, can be blocked by the carrier, no matter who is using it. And thanks to sophisticated algorithms, it is not easy to steal airtime by mimicking a SIM card (at least that's we're all being told!). Does anybody know whether there are other types of cellular networks offering such a feature (i.e. being able to use different mobile phones with the same number, without opening the door to phreaks)? Eric Tholome 23, avenue du Centre tholome@dialup.francenet.fr 78180 Montigny le Bretonneux phone: +33 1 30 48 06 47 France fax: same number, call first! ------------------------------ End of TELECOM Digest V15 #20 *****************************