Return-Path: Received: by massis.lcs.mit.edu (8.7.4/NSCS-1.0S) id AAA06595; Tue, 8 Apr 1997 00:42:04 -0400 (EDT) Date: Tue, 8 Apr 1997 00:42:04 -0400 (EDT) From: ptownson@massis.lcs.mit.edu (TELECOM Digest Editor) Message-Id: <199704080442.AAA06595@massis.lcs.mit.edu> To: ptownson@massis.lcs.mit.edu Subject: TELECOM Digest V17 #86 Status: R TELECOM Digest Tue, 8 Apr 97 00:42:00 EDT Volume 17 : Issue 86 Inside This Issue: Editor: Patrick A. Townson Another Technical Glitch Here (TELECOM Digest Editor) BA Favors Overlay of 215, 610 (John Cropper) Ex-USSR Country Codes Profile (Dave Leibold) NYS PSC Slaps ATT for "Slamming" (Danny Burstein) The Final Cellular Straw (John Higdon) New Telecom Banner Exchange (Judith Oppenheimer) Colombian Seminar in PCS - Looking For Speakers (Mario Castano-Gonzalez) PUC Hearings in Pa. Now Underway (Carl Moore) Re: Modem to Modem Flow Control (John Eichler) Re: Modem to Modem Flow Control (James Carlson) 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: * ptownson@massis.lcs.mit.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: Post Office Box 4621 Skokie, IL USA 60076 Phone: 847-329-0571 Fax: 847-329-0572 ** Article submission address: ptownson@massis.lcs.mit.edu Our archives are located at hyperarchive.lcs.mit.edu. The URL is: http://hyperarchive.lcs.mit.edu/telecom-archives They can also be accessed using anonymous ftp: ftp hyperarchive.lcs.mit.edu/telecom-archives/archives (or use our mirror site: ftp ftp.epix.net/pub/telecom-archives) A third method is the Telecom Email Information Service: Send a note to tel-archives@massis.lcs.mit.edu to receive a help file for using this method or write me and ask for a copy of the help file for the Telecom Archives. ************************************************************************* * TELECOM Digest is partially funded by a grant from the * * International Telecommunication Union (ITU) in Geneva, Switzerland * * under the aegis of its Telecom Information Exchange Services (TIES) * * project. Views expressed herein should not be construed as represent-* * ing views of the ITU. * ************************************************************************* Finally, the Digest is funded by gifts from generous readers such as yourself who provide funding in amounts deemed appropriate. Your help is important and appreciated. 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. ---------------------------------------------------------------------- Date: Mon, 7 Apr 1997 23:32:09 EDT From: ptownson@massis.lcs.mit.edu (TELECOM Digest Editor) Subject: Another Technical Glitch Here Since Sunday, the web version of TELECOM Digest has been unavailable due to a 'write system full, cannot write' condition on massis. I have been unable to get anyone's attention to this as of late Monday night but hope that sometime Tuesday the condition will be corrected. Anything at all going to the archives gets rejected and a zero-length file written in its place. Attempts to post the Sunday issue of the Digest resulted in the entire thing getting blown away as messages were rewritten will all empty files and the 'cannot write' message getting tossed at me a few hundred times as each file was getting (supposedly) posted. Hopefully the WWW version will be back soon, but this depends on getting someone at LCS/MIT to clean up the mess. PAT ------------------------------ From: John Cropper Subject: BA Favors Overlay of 215, 610 Date: Mon, 07 Apr 1997 18:13:36 -0400 Organization: lincs.net Reply-To: jcropper@NOSPAM.lincs.net Area Code "Overlay" Easiest, Most Economical For Customers in 215 and 610, Bell Atlantic Tells PUC "Geographic Split" Plan by AT&T, MCI And Sprint Forces Over One Million Pennsylvanians to Change Phone Numbers April 4, 1997 PHILADELPHIA - Adding a new area code using the "overlay" method would let all Southeastern Pennsylvanians keep the telephone number they have today when new area codes are added in the near future, according to Bell Atlantic. An alternative proposal by large out-of-state long distance companies would force more than one million Pennsylvanians to change their phone numbers causing tremendous inconvenience and expense for telephone customers. The Pennsylvania Public Utility Commission (PUC) will hold Public Input Meetings April 7-9 in the Philadelphia area to present the options available today to add two new area codes in the 215 and 610 areas. Bell Atlantic favors an "overlay" which would introduce two new area codes with the same boundaries as the existing 215 and 610 area codes. With overlays, no customers will have to change their telephone numbers. No business will have to incur the expense of advertising a new number, changing stationery, or ordering new signs for delivery trucks and storefronts. "We believe existing area code boundaries should stay the same, so that Southeastern Pennsylvania customers can keep their current phone numbers," said Daniel J. Whelan, president and CEO, Bell Atlantic-Pennsylvania. "Changing boundaries cuts up established neighborhoods, fragmenting both communities and business districts, as well as causing over a million customers to change their phone numbers." AT&T, MCI and Sprint favor a "geographic split" which would divide each of the areas covered by the 610 and 215 area codes roughly in half. Phone customers in one half would keep the existing area code and those in the other half would be assigned the new area code. Approximately 1.4 million customers would have to change area codes if Delaware and Montgomery Counties keep the 610 area code. Another 1.1 million customers would have to change phone numbers if Chester, Berks, Lehigh and Northampton Counties keep the 610 area code. The entire Philadelphia area would be disrupted by a geographic split of the 215 area code. Center City, North Philadelphia, West Philadelphia and South Philadelphia would keep 215. Several hundred thousand customers in Northwest and Northeast Philadelphia, along with portions of Montgomery County and Bucks County now in the 215 area code, would get a new area code. "The resulting confusion and fragmentation caused by these geographic splits will tear at the very fabric of our communities. Dividing towns, cities, counties -- even neighborhoods -- and giving a different area code to each side is neither socially nor economically fair to the people of Southeastern Pennsylvania," said Whelan. Whelan noted that residents in Southeastern Pennsylvania experienced a split only three years ago when the 610 area code was carved out of the 215 area. "The split advocated by AT&T, MCI and Sprint forces over a million Southeastern Pennsylvanians to change phone numbers just to make it easier for them to compete in the local phone market," he said. "We don't believe that these customers want to go through another split. We need to act soon to provide new phone numbers to meet increased demand," he said. "But let's make sure that Pennsylvania households and businesses emerge the winners." Bell Atlantic Corp. (NYSE: BEL) is at the forefront of the new communications, entertainment and information industry. In the mid-Atlantic region, the company is the premier provider of local telecommunications and advanced services. Globally, it is one of the largest investors in the high-growth wireless communication marketplace. Bell Atlantic also owns a substantial interest in Telecom Corporation of New Zealand and is actively developing high-growth national and international business opportunities in all phases of the industry. (JC Note: What BA isn't telling us is that 10-digit dialing would most likely would become mandatory in the affected overlay areas. If the PA PUC was smart, they'd mandate 10D dialing statewide NOW, and remove one barrier to area code relief ...) John Cropper, Webmaster voice: 888.NPA.NFO2 Legacy IS, Networking & Comm. Solutions 609.637.9434 P.O. Box 277 fax: 609.637.9430 Pennington, NJ 08534-0277 Unsolicited commercial e-mail is subject mailto:jcropper@lincs.net to a fee as outlined in the agreement at http://www.lincs.net/ http://www.lincs.net/spamoff.htm ------------------------------ Date: Mon, 7 Apr 1997 23:23:49 EDT From: Dave Leibold Subject: Ex-USSR Country Codes Profile Ex-USSR Country Codes Profile 4 April 1997 Below is a summary of the country codes that have formed in the wake of the USSR dissolution, along with some updated findings and reports. Additional or corrected information on any of these nations would be welcome (c/o dleibold@else.net). * Kyrgyz Republic country code 996 will take effect, at least in Canada, effective 1 May 1997, according to CRTC Telecom Order 97-464, based on Stentor Tariff Notice 433. There is no indication whether there will be a permissive dialing period involved or for how long such a permissive operation would remain. * Country code 992 was reported as a recent assignment for Tajikistan, which will be moving from country code 7 at some unknown time. * Uzbekistan has its own country code assignment, but I have no information if this is in service yet or what implementation dates have been set. * Kazakstan does not have a known separate country code assignment at present. It remains in country code 7 for the time being. * Russia seems destined to keep country code 7. * Recent news reports speak of some agreements forming between Russia and Belarus. While there is no outright reunification yet, there is expected to be much closer ties between the two nations. Whether this will lead to a reunification of telephone codes remains to be seen. In the table, "Effective" means the date at which the country code began service (which could vary according to the nation). "Mandatory" means the date at which the country code 7 is invalid for calls to that nation. There are a number of question marks since exact dates have not been collected in all cases. CC Nation Effective Mandatory Notes 370 Lithuania 1993? ??? Announced Jan 1993 371 Latvia 1993? ??? 372 Estonia 1 Feb 1993? March 1993? 373 Moldova 1993? ??? Announced Jan 1993 374 Armenia 1 May 1995 1 July 1995 Announced Jan 1995 (ITU) 375 Belarus 16 Apr 1995 1997? 380 Ukraine 16 Apr 1995 Oct 1995? 7 Kazakstan (no known changes) 7 Russia (presumably not changing) 992 Tajikistan ??? ??? Announced 1996-7? 993 Turkmenistan 3 Jan 1997 3 Apr 1997 Canada as of 29 Nov 1996 994 Azerbaijan Sept 1994? ??? Announced 1992 995 Georgia 1994? ??? ref: Telecom Digest Oct 1994 996 Kyrgyz Republic 1 May 1997 ??? ref: Stentor Canada/CRTC 998 Uzbekistan ??? ??? Announced 1996? (ITU) Details courtesy Toby Nixon, ITU, Stentor (Canada), CRTC (Canada), TELECOM Digest (including information collected for the country code listings). ------------------------------ Date: Mon, 7 Apr 1997 12:26:24 EDT From: Danny Burstein Subject: NYS PSC Slaps ATT For "Slamming" Among other things, the PSC ordered ATT to "cease ... switching customers to it without legitimate authorization." STATE OF NEW YORK PUBLIC SERVICE COMMISSION At a session of the Public Service Commission held in the City of New York on March 5, 1997 COMMISSIONERS PRESENT: John F. O'Mara, Chairman Eugene W. Zeltmann Thomas J. Dunleavy CASE 97-C-0229 -In the Matter of Slamming Complaints Received Against AT&T Communications of New York. ORDER DIRECTING RESPONSE (Issued and effective March 21, 1997) BY THE COMMISSION: AT&T Communications of New York (AT&T) holds a Certificate of Public Convenience and Necessity to resell all forms of telephone service in New York State. During the period from January 1, 1994, through January 31, 1997, the Consumer Services Division received 5,284 complaints related to slamming, of which 588, or 11%, were against AT&T. Sixty-six percent of the AT&T complaints, or 389, were received between January 1, 1996, through January 31, 1997. An analysis of the complaints received by the PSC against AT&T on a month-by-month basis from January 1996 to January 1997 indicates that the number of complaints has significantly increased by 143 percent from 1995. We reviewed a ten percent random sampling of slamming complaints against AT&T and found that they fell into three categories: letters of authorization (LOAs) with errors, no LOA's, and incomplete records of contact. In 71% of the cases, service had clearly been switched without authorization. In the 29% remaining, reasonable doubt exists due to the fact that not enough information is available at present to determine if the service agreement forms that AT&T claims to have are authentic or not. Whether the company or its sales and marketing agents or any subcontractors submit requests for carrier changes, the company bears the burden of ensuring that its new customers have knowingly and voluntarily chosen to switch to AT&T's service, for ultimately, the company will bear the penalty should any unauthorized switches occur. Currently, all companies are obliged to follow the Federal Communications Commission's rules and procedures regarding customer transfers and verifications of change request orders. In addition, all telecommunications companies operating in the State of New York must comport with the Public Service Law, regulations pursuant to the Public Service Law, and orders of this Commission. While on a monthly basis the number of slamming complaints against AT&T may be small, relative to AT&T's size, in the aggregate, the number of complaints are significant. An analysis of the complaints against the company suggests that AT&T has been utilizing questionable marketing practices. Thus, although the ratio of complaints to customers is small, because no customer should experience this practice, action against AT&T is warranted. AT&T is hereby on notice that we continue to receive a high level of slamming complaints against it from consumers. Accordingly, AT&T is directed to cease submitting carrier change requests for its service without legitimate authorization. AT&T must also submit to the Commission, within thirty days of this order, its plans to reduce and eliminate slamming complaints at the Commission. The Commission orders: +_____________________ 1. AT&T Communications of New York is directed to cease submitting carrier change request orders or switching customers to it without legitimate authorization. 1 2. AT&T Communications of New York shall submit within thirty days of this order ten copies of specific plans to reduce and eliminate slamming complaints. 3. Staff will review AT&T Communications of New York's plans to reduce and eliminate slamming complaints and report to the Commission. 4. This proceeding is continued. By the Commission, (SIGNED) JOHN C. CRARY Secretary _____________________________________________________ Knowledge may be power, but communications is the key dannyb@panix.com ------------------------------ Organization: Green Hills and Cows Date: Mon, 7 Apr 1997 13:10:35 -0700 From: John Higdon Subject: The Final Cellular Straw As we all know, the aging cellular network in this country (using AMPS) has absolutely no security built into it. Cloning is a way of life. In the past year, cellular equipment providers have produced a system that they hailed as a breakthrough in fraud detection/prevention: RF fingerprinting. Simply, this is a system that detects and stores details about a legitimate user's cellular phone's transmitter. On the theory that no two transmitters would create the same profile, the system compares the fingerprint of a phone attempting to make or receive a call with the stored profile. If they don't match, the call is dumped. After months of using my handheld Motorola exclusively in its car adaptor, I needed to use it has a handheld. Important, expected calls never got through. Why? It turns out (verified by GTE Mobilnet's control center) that my handheld was rejected by the fingerprint detector which was expecting to see the car transceiver. Although the cellular industry is notorious for inconveniencing customers in the name of preventing fraud, this is the ultimate outrage. As far as I am concerned, any procedure that errs on the side of the denial of service to a legitimate customer is unacceptable. Since GTE did not agree with me, I am no longer a customer. I have, this day, activated a Pacific Bell PCS phone. Say what you want, but at least Pacific Bell knows that people depend upon telephone service and does not go out of its way to throw banana peels in front of customers who expect to be able to rely on communications. There are no doubt others who feel this way. John Higdon | P.O. Box 7648 | +1 408 264 4115 | FAX: john@ati.com | San Jose, CA 95150 | +1 500 FOR-A-MOO | +1 408 264 4407 | http://www.ati.com/ati/ | [TELECOM Digest Editor's Note: The best cellular service I have ever experienced without exception is Frontier. Admittedly, they just resell other carriers (in my case, Ameritech) but their pricing is very good, no contracts are required, and you can use any cellphone you want. The one catch is, you have to be a customer of theirs otherwise in order to be a cellular customer. I have an 800 number of theirs, and one of my phones at home is defaulted to them for long distance calls. Ameritech's rates are pretty good to start with, and Frontier gets a rather deep discounted 'corporate' rate which they pass along to their customers. Basically, I think their cellular service is intended as a lure to get you to sign up for their long distance. I pay ten dollars per month and 35/18 per minute on calls. It is month-by-month, and all you have to do is give them the ESN of the phone you want to use (and, obviously, know how to program it). The rate you will pay depends on the deal they have cut with the 'B' (in most cases) carrier in your community. I have to admit that in some cases a result Frontier is higher than what I pay here, but they will still be lower than what you would pay the 'B' carrier in your community. If you are somewhere in Ameritech's five or six state territory you would get the same rates I am paying, and good Ameritech service at a discount. Remember, you have to default a line to them for long distance and/or subscribe to their 'Call Home America' 800 service which is also a pretty good deal in order to qualify for cellular. Since they give a $25 credit to existing customers who make referrals to them, if you feel so inclined, tell them I mentioned it. PAT] ------------------------------ Date: Mon, 07 Apr 1997 11:55:22 -0400 From: Judith Oppenheimer Reply-To: joppenheimer@icbtollfree.com Organization: ICB Toll Free News Subject: New Telecom Banner Exchange ICB Toll Free News has launched The Telecom Reciprocator, a telecom-only banner site. Also launched is a business banner program for biz-to-biz sites that want exposure to a telecom readership. Both can be found at http://www.icbtollfree.com, click on index link "Join ICB's Telecom Banner Program" or "Join ICB's Business Banner Program." New articles under "Industry News & Analysis" include our assessment and advice regarding 877 ("REPLICATION: TO BE OR NOT TO BE is not the question"), and new articles about 800 dial-up internet access. And finally, last week Starting Point viewers voted ICB Toll Free News a Starting Point News 'Hot Site'! We thank all who voted for us. Judith Oppenheimer Publisher ICB TOLL FREE NEWS - 800/888/global800 news, analysis, advice. http://www.icbtollfree.com, mailto:news-editor@icbtollfree.com Judith Oppenheimer - 800 The Expert, ph 212 684-7210, fx 212 684-2714 mailto:j.oppenheimer@worldnet.att.net, mailto:icb@juno.com ------------------------------ From: Mario A. Castano-Gonzalez Subject: Colombian Seminar in PCS - Looking For Speakers Date: Mon, 7 Apr 1997 09:39:01 -0500 Hello ... We at CINTEL are organizing our second ANNUAL SEMINAR IN PCS to be held June 18 - 19 in Bogota, Colombia. Our aim is to help to understand these new services, technologies and regulation to the Colombian companies that will start offering PCS in our country in September, 1999. Last year's seminar was focused in technology (GSM, IS-136, IS-95). This year we are deeply interested in analyzing how has been carried out the deployment of the services, including marketing strategies. We think that the experience in USA and in Chile will be of special value to the attendance. That is why we are interested in to contacting some speakers from US service providers that are now offering PCS and that would like to share their experiences with us in a 45' conference. We are expecting 100+ attendants from the government, private and public telcos and universities, 5 official sponsors from the industry, and we will also have a commercial exhibition. All of you that might be interested in participating please contact me at the addresses provided. Regards, Mario A. Castano Director, Planning Office Centro de Investigacion de las Telecomunicaciones - CINTEL Av 9 118-85 Bogota Colombia Tels: +57 1 620 8307 - 620 8137 Fax: +57 1 214 4121 Email: m.a.castano@ieee.org ----------------------------------------------- CINTEL (Centro de Investigacion de las Telecomunicaciones, Telecommunications Research Center, established 1994) is a private, non-profit organization with 41 shareholders that represent the most important companies related with the telecommunications business in Colombia, including 23 local and long distance telephone service providers, universities, telecomms equipment providers and governmental institutions. We provide R&D, standardization, certification, consulting and training services to the whole telecomms sector in our country. Our objective is to collaborate in the technological development of the telecomms companies and services in Colombia. ------------------------------ Date: Mon, 7 Apr 97 16:32:23 EDT From: Carl Moore Subject: PUC Hearings in Pa. Now Underway It's the lead story on KYW news-radio (Philadelphia) that the Pa. PUC is commencing hearings on relief for 215 & 610. Same proposals as in many other places: geographic splits or overlays. (I recall hearing in the Digest that 412 already has area code 724 approved as a coming overlay.) [TELECOM Digest Editor's Note: John Cropper mentions this in detail in another message in this issue. Do you think they will make the right decisions, or give in to pressure from special interests? PAT] ------------------------------ From: John Eichler Subject: Re: Modem to Modem Flow Control Date: Mon, 7 Apr 1997 09:35:56 -0500 I might be able to add a little something to what Jeffrey Rhodes wrote. There are two rates which must be considered when talking about modem communications. One is the rate at which the computer itself feeds/accepts data to/from the modem. The other is the rate at which the modems actually talk between themselves. Concerning the first rate. The values of 2.4K, 4.8K, 7.2K, 9.6K, 19.2K, 38.4K, 115.2K etc. are based upon the data rates of serial ports on most computers. There are set recommended frequencies that are usually used to clock the UART (Universal Asynchronous Receive Transmit) chips. These rates are simply the rates at which the modem's DSP communicates with the computer itself. It makes no difference which rate is chosen as long as your computer is capable of accepting data at the designated rate. There are two primary considerations with regards to this. First, a buffered UART must be used (such as the 16550) because many of the newer operating systems are not capable of responding to I/O requests rapidly enough so the input in particular must be buffered from the modem until the OS can get around to reading it in. The 16550 can buffer 16 bytes of input (and output) and thus a computer can read in several bytes in a burst-type mode. To coordinate the flow between the computer and the modem this is where flow control is normally used. There are a couple of primary ways this is accomplished. One is by embedding certain codes (xon/xoff) within the byte stream feed to/from the modem. The others are using hardware signals such as the DTR/DSR pair or the CTS/RTS pair. Second, if data compression is used (i.e., that provided by the modems themselves), the actual data rate between the computer and the modem can effectively be 3 or 4 times the rate at which data is transmitted by the modem. For example, assumming that two modems are communicating at 14.4K bps with compression implemented, the sending and receiving computers might have to transmit/receive at 4 times this rate (i.e., 57.6K bps) to fully utilize the transmission channel. This puts a burden on the computers to be able to keep up with the faster rate. This also is why one should set the transmission speed to/from the modem at a much higher rate if they are going to turn on data compression within their modems. Now the rate at which the modems talk between themselves is, as Jeffrey states, usually determined by the modems themselves. Most modern modems implement a 'fall-back' scheme at which they negotiate between themselves which is the rate to be used. Generally they first try at the highest rate possible and if this rate won't work, they go to the next lower rate and try that. (It may be noted that some modem protocols actually will dynamically adjust the rate of transmission depending on line quality and error rates encountered.) These rates are the transfer rates defined by the ITU in its various standards. Although it is possible with many modems to specify that a particular connection speed should be used, it is usually better to let the modems determine it themselves particularly over a public switched telephone network. Just specify the highest rate at which the modem can operate as the starting point. The main area of confusion when talking about speeds is usually extrapolating the modem transmission rate from the computer to/from modem rates. The clocking of the UARTs transmitting data between a computer and a modem is completely asynchronous from the speed at which the modems communicate between themselves. (This is not true for binary synchronous communications which is a horse of a different color and generally not used by most folks.) Don't get the speeds mixed up. Just make sure that the computer that is being used to talk to the modem has a higher rate specified than the modem is capable of receiving data at. For transmitting data it doesn't matter since the modem will just transmit meaningless info just to keep the connection alive. But for receiving, note the comments made above. I hope this might clear up a little of the confusion in this thread. John Eichler ------------------------------ From: James Carlson Date: Mon, 7 Apr 97 09:47:59 EDT Subject: Re: Modem to Modem Flow Control > there is no need for modem-to-modem flow control. If the modems are > both V.34 modems, the connection rate could be 28,800 because V.34 > uses some kind of HDLC protocol where information is encoded in > packets or frames (I think). This provides flow control since only so > many packets or frames can be sent without being acknowledged. Again, > there is no need for any kind of XON/XOFF thing between modems. Pretty close. All high-speed (>=9600bps) modems use synchronous links between the modems. On top of this, they use LAP-M (which is an HDLC-based protocol) and V.42 or V.14 to adapt asynchronous traffic to the modem's synchronous interface. The LAP-M protocol is basically a reliable transport protocol which uses retransmission timers and sequence numbers to achieve reliability. In this protocol, flow control is done by having the receiver indicate that it's willing to receive more data, and not necessarily by a "flow off" message as with XON/XOFF. (Though, confusingly, V.42 does provide a way to carry RS-232 signals end-to-end. Sigh!) > I think I read that PPP protocol connections to an Internet Service > Provider are better if you turn off the flow control and error > correction of ARQ, since this only thrashes with the same PPP > functions at a higher layer? PPP does not do flow control or error correction at all. TCP, which is one of many, many protocols which can run over PPP, does do both flow and congestion control. Use of error control protocols on top of one another is generally a bad idea if the error recovery time of the lower level is similar to the normal round-trip-time. This does mean that it's *sometimes* a bad idea to run TCP over a PPP link with error control turned on. Unfortunately, no solid rule can be made, and leaving error control on in the modems *usually* does no harm. > Maybe someone will correct my misconceptions, but in general, I think > today's protocols and modems provide modem-to-modem flow control > without XON/XOFFs. Of course, hardware RTS/CTS flow control between > each PC and its modem is needed to run 115,200 into a modem in the > first place, and this is needed to deliver data at a higher DTE rate > than the transmission rate so that compression techniques will offer > any benefit. Theoretically, V.42 can give >28,800 bps with > compression, but only when much >28,800 bps are delivered by the DTE. Right. Note, though, that 28.8Kbps at the modem link level (DCE) is a synchronous data rate, and 115.2Kbps on the DTE is an asynchronous data rate. The two are not directly comparable. 28.8Kbps DCE is about 3600cps (not including overhead). 115.2Kbps DTE is 11520cps (assuming 8 bits, no parity, one stop bit). ------------------------------ End of TELECOM Digest V17 #86 *****************************