I use Skype for everything as I don't have a land line.
I pay �1.50 a month that allows me call any geographical landline number in the world for 3p, regardless of the length of the call.
Skype to Skype is free. I also have SkypeIn, which allows landline numbers to call me - as far as they are concerned they are calling a normal UK number and get charged as if they were.
This has a big advantage. Where ever I am I can log in to Skype and see who has called me and when, access my voicemail and so on exactly as if I were at home.