Ok, not for landline users, but if you have an iphone, there is an app called "Viber" which is for free calls, apparently:
http://www.viber.com/
As I don't have an iphone, I can't comment on how good/bad it is, just saw a friend mention it on FB.
GG, unfortunately calls to international mobiles on Orcon plans are charged at a hire rate.
http://www.orcon.net.nz/home/page/or...line_and_tolls. Calls to Irish mobiles are charged at $0.61/min, assume the US is at a similar rate. (that's from the charge on my last bill in case its not easily visible on the Orcon site)