If you use VoIP telephone in software, it is called software based VoIP Phone. You can use it as an IP phone by connecting the same to the computer. You should install appropriate audio hardware in this software based VOiP phone. This audio hardware includes any of the following items- an USB based phone handset, microphone, headphones, sound card with speakers. Soft phones are cheaper than hardware based VOiP phone, but soft phones are inferior to hard phones. Check the Internet to get more info and availability of software based VOip Phone.

In the online, you can download freely the software required for the function of the software based VOip phone. e.g. 3CXPhone. This phone- 3CXPhone softwre is available online. You can use this software to use your PC or laptop as a phone. The 3CZPhone should be connected to a VoIP PBX or VOiP provider to make calls to any landline number. Have a Happy New Year-2010!!!