I've had some computers that had SP2 I had work on, that just screwed up the connections of the telephone modem. I usually reinstall sp1 (in 1 case I reinstall win 98) and the problem would go away.
but Mehdi, you have not answered this question. did you enable your telephone modem in the bios? as much as I read through this post, this seem like this is your problem.
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