IIRC the actual NA FCC allowed maximum speed a 56k modem is allowed to
provide is around 52kbps. It's a moot point though since no one will
ever actually see that speed unless they live right next door to their
Cental Office. I'm 1.2 miles from my CO and the best speeds I ever saw
were around 47k. The norm was more often something around 43k (all
rounded off numbers).
As for an AT command to check line quality, that would be a function of
your modem, not XP. Some modems have that switch, most don't, so check
your documentation to be sure.
There ARE a few things you can do to help, but you should realize that
"connection speed" isn't really the most important number.
"Through-put" is more important. You can have slower connection speeds
that will have much higher through-put speeds than the higher connection
speeds. So the first thing you really need to be able to do is keep
track of through-put speeds.
I'm making up numbers here, but say you get a thru-put of 10 kbps at
33.6 connection speed, but you only get 8 kbps thru-put at 36k
connection speed. What you would actually want in that case is 33k
connection speed then, because it is passing data faster than the higher
connection speed.
The reason for that would be that the higher connection speed is
reaching the limits of the phone line and more and more packets are
having to be resent due to errors. At the slower connection speed, the
wiring introduces less distortion, ringing, etc., and thus has to do
fewer packet resends, resulting in a higher thru-put per second.
At the end of this I'll post a few lnks that might help you but it's
been a long time since I've played with dialup, so they might only be
enough to get you started rather than good answers or explanations.
Another thing you can do is to set your MTU (Maximum Transmission Unit)
to match the modems at your ISP that you connect to. There's a specific
setting for V.92 or V.94 modems, so I'll try to find that. What it does
is makes sure your buffers going in and out are full and not partials,
allowing empty parts of the packets. Making up numbers again, if one
packet can handle 100 characters, and you send or receive 101
characters, then it requires TWO packets, twice the time, to get that
one leftover character. The actual number will be around 1400 to 1500,
I think; somewhere in that range.
Here's what I can locate quickly on links/URLs. There is a LOT of info
available and many many tools still available. Dialup is alive and well
despite many comments to the contrary.
N O T E : Web Accelerators and other "magic beans" that claim to speed
up internet connections by factors of from 3 to ten are almost ALL
hoaxes! Don't be suckered by a $19 program to let you surf the web "5x
faster".
http://www.mdgx.com/56k.htm
http://www.wurd.com/instcon_thruput.php
http://www.pctools.com/guides/registry/detail/280/
http://www.mdgx.com/modem.htm
http://www.techtalkz.com/tips-n-tricks/41-how-make-your-56k-dial-up-m...
http://www.wizcrafts.net/baudtest.html
http://en.wikibooks.org/wiki/Transferring_Data_between_Standard_Dial-...
http://www.modemsite.com/56K/x2-thru.asp
http://www.filetransit.com/view.php?id=3548
NOTE: I do NOT condone or otherwise recommend any of these sites, nor
do I claim any particular usefulness for any of them. Proceed at your
own risk.
HTH,
Twayne`
