I went to the site and it seems that you dont need a phone. This is a voice over IP application and all you will need is speakers and a microphone for your PC.
Listed on the site:
System Requirements
In order to use Skype software, your computer must meet the following minimum system requirements.
Minimum System Requirements:
* PC running Windows 2000 or XP
* 400 MHz processor
* 128 MB RAM
* 10 MB free disk space on your hard drive
* Sound Card, speakers and microphone
* Internet Connection (either dial-up: minimum 33.6 Kbps modem, or any broadband: cable, DSL, etc.)
However, in order to take advantage of all of the advanced features of Skype and to experience the best sound quality possible, we highly recommend the following configuration.
Recommended System Requirements:
* PC running Windows 2000 or XP
* 1 GHz processor
* 256 MB RAM
* 30 MB free space on your hard drive
* Full duplex sound card (most sound cards made after 1998), headset
* Cable, DSL or equivalent broadband connection to Internet