No dial tone @ modem

Got my brand new Dimension 3000 out of the box and connected it up but can't get the modem to work.  Have tried numerous things including Modem Helper which tells me there is a dial tone coming into the modem but the modem can't hear it.  I get a dialog box up that tells me "Phone line in use".  Have connected Acer Notebook to same phone line and can dial out successfully.  Tried different phone lines and same problem with my Dimension 3000.  When I try to connect I hear absolutely nothing as opposed to other PCs where you hear the dial tone then the modem dialling out.  Have sent email to Dell support but waiting to hear back.  Bit of a nuisance as I have to go to friend's and use her computer.  Any other ideas on what I can try. 

 

I note that msgoodie2shews seems to have the same problem - as I am new to the forum didn't know if I should add my woes to her thread.

 

Cheers