Not a software question. It's a hardware issue.
All fax software requires an analog phone line. No fax software will
function with DSL lines. With some DSL connections you can obtain a DSL line
filter suitable for connecting a standard analog voice line to the DSL line
and can then connect an analog fax modem to that line.
If you have no analog modem or phone line, you will need to use a fee based
Internet Fax Service. Several are listed here: http://www.savetz.com/fax/