Regarding mysterious dialing:

I think there are some Trojan horses distributed by various
hacking groups which try to do this sort of thing as well.
Most of them seem to pick on machines they think have DSL
or cable connections, but I wouldn't at all be surprised
to find a dial-up one, too.  These folks have programs running
all the time, looking for unsecured computers so they can plant
a small program that can be used for various nefarious purposes.
Periodically, these things need to "contact the mother ship",
as it were, so perhaps that's what's going on here.

Also, I'd be suspicious of spyware downloaded to your machine
as part of web surfing.  I routinely use SpyBot on mine to
clean up that stuff.  From what I hear, some of those things
may try to establish internet connections, too.

Hope it helps,
Henry Bibb

              The NOSPIN Group is now offering Free PC Tech
                     support at our newest website:
                          http://freepctech.com