The closer he is to the CO, the more likely he is to be getting excessive
loop current which a lot of modern modems don't like one little bit.
Loop current should be about 25mA max - if he's *that* close to the exchange
chances are it's excessive (high loop (> 30mA) current = difficulty
connecting, difficulty staying connected, slow transfer rates or a
combination of all three (the higher the loop current, the worse the
potential problems). VERY high loop current (> 65mA) = potentially fried
modem - maybe not immediately but any time, could be weeks, even months).
The problem is worst in large rural areas, where the telco will tweak up the
lines to achieve maximum distance - don't forget customers FAR from the CO
need about 20mA minimum, otherwise they wouldn't be able to hear while on
the phone! Ironically phones work best (most audible) with high loop
current, while modems prefer it as low as possible.
Problem is, the specifications were written decades ago, the telco is only
obliged to stay within 20mA to 120mA range, because decades ago with carbon
headsets etc you needed the current to achieve the necessary volume. I defy
anyone to connect a modem to a line with 120mA LC and it survives... ;-(
Regards
Bob
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