Free phone calls all around the world from your computer
VoipBuster offers free calls phone to any regular land-line in various popular destinations
The software is free to download and you can always get the latest version here. If you have any problems using VoipBuster, please first make sure that you are using the most recent version of the software. 
To download the VoipBuster to your computer, simply click the download link. Save the installation file to your computer. Be sure to remember where you saved the file (for instance the Desktop).
Installation
Double-click the installation file you just downloaded to start installing the VoipBuster on your computer.
VoipBuster starts automatically each time you start windows. With the VoipBuster always running, other users will be more likely to find you online. You can change these settings at any time from the VoipBuster program by selecting "options".
Starting the VoipBuster for the First Time
The first time you start the VoipBuster, you will be asked to choose a User Name and password. The User Name and password fields are required in order to use the VoipBuster. You can choose any name but it must be at least 6 characters in length. If the name is already in use by someone else you will have to try another name.
Making your first VoipBuster call
For a call to any online VoipBuster user, simply enter the username in the textbox and click the dial button. For a call to any regular phone, enter the desired number in the textbox and click the dial-button. If you are calling a land line in one of our free calls phone destinations ( Andorre Australie Autriche Belgique Canada Chili Chypre Corée Du Sud Danemark Espagne Estonie Etats-unis (+mobile) Finlande France Guam Hongkong (+mobile) Hongrie Irlande Islande Italie Japon Liechtenstein Luxembourg Malaisie Monaco Norvège Nouvelle-zélande Panama Pays-bas Porto Rico (+mobile) Portugal République Tchèque Singapour Suisse Taïwan ), the call will be placed at no costs at all. For all other calls, you will be asked to buy credits first.
Calling with VoipBuster
There are several ways to call with VoipBuster:
From the textbox, enter the User Name of another VoipBuster user, or the desired phone number and press enter.
Double-click a User Name in your contact list.
Use the dialpad to make a call just like you do on a regular phone.
Or use the keypad on your PC.
Please note that when you call a number (even if it's local) you should always dial 00 + countrycode + areacode + subscribernumbe.
source : http://www.voipbuster.com/