There use to be quite a few of these free phone companies around, but not any more.
This isn't a new deal, but it's one I have been taking advantage of while my Girlfriend is overseas.
All you have to do is sign up, credit your account with 10 Euros. (Paypal) and you get free calls for six months to land lines (see bellow) and mobiles(UK & US), there are some limitations. Calls cut off after 60 mins (although you can call them right back) and there is a limit is 300 Mins per week (although I have gone over this a few times without any penalty). You can use the free soft phone software on their website or any SIPP compatible device, I am using a unlocked engin cordless phone I bought on ebay for $50. Calling within Australia is also free but you have to use 0061 before the number .i.e. 0061 7 5555 6969
After your 6 month trial you can still make calls by using up you 10 Euros credit, and with their call rates it should last a while.
If you need more than 300 mins per week you can also sign up voipbuster.com (same company) who offer the same sort of deal with 300mins with them as well.
List of free call countries
Argentina free*
Australia free*
Austria free*
Belgium free*
Canada free*
Czech Republic free*
Denmark free*
France free*
Germany free*
Hong Kong (+mobile) free*
Hungary free*
Ireland free*
Italy free*
Luxembourg free*
Malaysia free*
Monaco free*
Netherlands free*
New Zealand free*
Norway free*
Panama free*
Poland free*
Portugal free*
Puerto Rico (+mobile) free*
Russian Federation free*
Singapore free*
Slovenia free*
South Korea free*
Spain free*
Sweden free*
Switzerland free*
Taiwan free*
United Kingdom free*
United States (+mobile) free*
Yet another Betamax company.
They have actually set up quite a few of those free call websites. They are SIP based but call quality is pretty mediocre. I've used them quite a few times (VoIP stunt, another Betamax company), but basically give up after too many complains from the people I called :P