[clug] Silly modem question

[Michael Still]

So, I'm roughing it and now using a modem. I haven't had to configure one
of these in a couple of years, so I'm a little rusty...
I have pppd configured to the point where it dials the ISP, and the ISP
answers. Then I can hear the modems negotiate. They burble a bit, appear
to drop back to a previous burbling phase, burble some more, and then I
get told "NO CARRIER".
The machine is a Pentium 133, with the serial ports on the mother board.
The modem is an external 56k.
Is there anything obvious that I might be missing?

Thanks,
Mikal