Again, don't know much about your setup. It sounds like you have an analog phone. I have never seen these, but if a fax comes in to that line, it could tie up your line for awhile and vice versa.
If you are really serious about PC to Fax and Fax to PC, I would highly suggest a networkable fax machine or MFP. You can get a good one at a good price with Brother, although everyone knows I am not big on Brother.
