Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: westmark!dave@uunet.uu.net (Dave Levenson) Newsgroups: comp.dcom.telecom Subject: Re: Do Modem Users Congest The Phone Network? Message-ID: <1760@accuvax.nwu.edu> Date: 3 Dec 89 14:20:00 GMT Sender: news@accuvax.nwu.edu Organization: Westmark, Inc., Warren, NJ, USA Lines: 49 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 9, Issue 548, message 2 of 8 In article , eli@robechq.UUCP (Robec Corporate Office) writes: > Ohh, I'll probably get my head handed to me on this one, since I'm not > really sure what I'm talking about, but I thought the reasoning behind > added charges for modem usage were because modems take up greater > bandwidth, in fact the bandwidth of several voice calls. Is this > true? No, it is not true. A modem using a dial-up voice-grade circuit uses the same bandwidth as any other call dialed-up over the same circuit. The added charges are based upon the presumption that average call duration is longer for modem users. The telco networks are engineered based upon assumptions about average number of calls and average call holding time per subscriber. Business voice users, residence voice users, and dial-up data users have all been characterized by the traffic engineering folk. They design their network according to the number of each in the area it will serve. When they build a central office, or an inter-office network, they engineer it with enough resources to provide a 1% blocking factor. That means that during the busiest hour of the busiest day of the week, one call out of 100 will be blocked for lack of some network resource. The economy-of-scale that is realized in this way is taken into account when rates are set. If the average useage per line changed significantly, then the rates need to change. The point recently made here, however, is that modem calls are getting shorter -- as modems get faster, and as more intelligent devices get placed behind them. A PC running UNIX and communicating with its netnews server over a UUCP link for a few minutes a day is quite different from a dumb terminal whose user logs into a netnews machine and reads the news for hours at a time. What is wrong with the telco's reasoning is categorizing all modems the same. It has also been pointed out here that some people talk to each other longer than some machines do. When I was in high school, it was not unusual for my teen-aged sisters to show line occupancy of about 36 ccs (that's 100% -- i.e. 3600 seconds per hour) of line capacity for parts of every evening. But at the time, a 'teen line' was available at a discount! Dave Levenson Voice: (201) 647 0900 Westmark, Inc. Internet: dave@westmark.uu.net Warren, NJ, USA UUCP: {uunet | rutgers | att}!westmark!dave [The Man in the Mooney] AT&T Mail: !westmark!dave