Not a fan of Skype for a number of reasons, mostly around costs if you want a proper number, and the fact that it needs PC on.
I personally use a SIP based solution, with a hardware SIP to PSTN adapter.
The provider I currently use is sipgate.co.uk (coz its free to sign up, and you get a geographic number), and a Linksys PAP2 adapter so I can plug in normal phone (or phone system in my case). Visiting anyone for a few days? Just take the PAP2 and plug into their broadband (adjusting firewall if necessary)
SIP, though, like most proper VOIP protocols, is time dependent, so if your broadband is being thrashed, you can get dropouts, bit like mobile phones in weak areas.
Its free, I suggest anyone try it (with software 'phone'), if it doesn't work for you, then nothing lost...