The dsl modem connects directly to the phone line.
The faxmodem or HP 4110 connects through the dsl filter to the phone line.
They were nice enough to supply a phone line splitter and filters, but in your case, no one told you (or where's the manual) to install the filters, etc.
The HP 4110 does NOT connect to your PC via said phone line, so you connect your usb line to it...
Ever since we put a Linksys WRT54G wireless router on my SBC DSL line, I can send faxes, but not recieve. I was told by someone at Linksys support that I have to connect my HP 4110 all-in-one to the phone line before the router. This means I won't be able to send a fax directly from the computer, but will have to print things and feed them through the fax manually.
Is this correct? Any way to make it work as before? I'm using Windows XP Home.