yea, as long as you have your modem drivers installed, which if you haven't reformatted since u bought it, then they should, it's just you need a software application to do so, windows used to have a Telephony application in previous windows versions... 98 and below, but got dropped due to VoIP technology's, but yea, just need the software, some even support caller id, if you have it on with your local phone company, then all you need is a microphone, or headset, here is a example of the kind of software i am talking about.
http://www.download.com/Advanced-Cal...ml?tag=tab_scr
is it necessary though??? if you live in north america, they offer free calls anywhere in the U.S. and i think they just added support to call canada just download the software
www.skype.com , it's really a popular app and goes over the internet and calls landlines..great quality if you have decent broadband, no ghosting or echos.