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Forcing a certain connection speed?
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MLeRoux
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I've been having problems with random PPP disconnections since I bought a new iMac DV with the internal 56K modem. I don't know if I'll ever be able to tell whether my ISP or the software is at fault, and the ISP is no help.
I have noticed that the problem disappears when I tell the Modem control panel to use the Apple Internal Model 56K (v.34) script (I may have the name slightly incorrect). This script essentially forces the modem to connect at 28800 or 33600 at the most.
Has anyone successfully modified the Apple modem script to connect at a certain speed, say somewhere between 33600 and the 52000 I usually get? I'd like to know what changes are necessary. I cloned the script and changed a few things with a text editor but so far I haven't been able to get it to work.
Mike
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Professional Poster
Join Date: Mar 1999
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Dedicated MacNNer
Join Date: Oct 1999
Location: Austria
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Mike,
instead of "56k" the latest generation of modems should in fact be called "53k", because of some glitches in the implementation of V.90 (at the the telco companies, as I recall it) just this speed can be reached at optimal line conditions. Alas, line conditions are rarely optimal with analog connections, so speeds between 44k and 48k should be a good value and you should not expect much more in everyday use.
Alos, forcing a modem to connect just at a certain speed rate does not seem a good idea to me, as you are ignoring the negotiation capabilities of modern modems which makes them flexible in terms of changing "real world" line conditions.
Just an addition to what wlonh wrote.
Walter.
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Mac Enthusiast
Join Date: Oct 1999
Location: San Diego, CA, USA
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The FCC forces modem manufacturers to not go above 53K. It's an old rule which I can't believe hasn't been removed. It has to do with voltages on the line. To do above 53K would cause the voltages to peak above what is allowed.
Of course, almost no phone line is clean enough to hook up reliably above 50K anyway.
(Now that I say that, I am prepared for the onslaught of people reporting "I hit 53K all the time")
drewman
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Admin Emeritus 
Join Date: Oct 1999
Location: Zurich, Switzerland
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Indeed, I often (but not always) get 53000bps. ;-)
But actually, I think it is not modem manufacturers that are required to limit the speed, but the ISPs. 56K modems can theoretically reach 56K outside the US, although in all fairness, most foreign countries, even western Europe, have noticably "dirtier" lines than the US. (Here, a standard iMac on clean lines, such as mine in MD, often reach 50Kbps or even 53K, while in Switzerland, I have never seen an iMac or ANY 56K modem reach more than 48K, and 40K or 44K was the rule.)
tooki
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