No. Since a telephone line is required to send a Fax transmission, this is obviously not possible with a DSL modem, because your computer is not directly connected to the phone line. However, there are several commercial services on the Internet that offer faxing services over the Internet via the use of email; please consult a search engine for more details.
Also, if you still have a Dial-Up Fax modem in your computer, you can configure it to be enabled only when you need to send faxes. This feature is usually installed as an available printer in the system and you simply "print" to the fax driver to send faxes.
PenTeleData Technical Support does not offer assistance in any way for sending faxes using your Broadband DSL Modem service, nor do we support sending fax transmissions with your Dial-up modem.