would they not be be better off getting a voip adaptor and using a normal phone? Depending on what provider they are going to use.
Voip on computers are a pain as it means the computer have to stay on.
i have a Linksys adapter, which was cheap and works well.
Desktop machine now powered by windows 8 pro 64bit, no dreaded metro and Linux , laptop by Linux
ALLPAY Wireless broadband