I was not able to get the software modem on my Dell Latitude D500 working for the last few months. Actually it never worked with 2.6 kernel series, I had a 2.4 kernel installed only for the half-binary PCTel modem driver. That day :), I decided to take another chance on it.

After a bit of Googling magic I was able to get my:

0000:00:1f.6 Modem: Intel Corp. 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Modem Controller (rev 01)

modem working, by installing sl-modem-source and sl-modem-daemon packages of Debian. At least it was able to say NO DIALTONE, which is a good indication for me!