can't fax

From what i heard, you have to be connected to a phone
line. You can't fax from a dsl or cable connection
-----Original Message-----
I set up the fax on my computer but it does not send
fax's. do I need to plug in my phone line (I have cable)
or can I fax straight from my pc? If so what do i need
to
do to fax from my pc. thanks
.