Callback is a service which allows you to make cheap international calls all over the world. The way the system works is very simple. When you contact the service provider you will be granted access number which is your connection to the line maintained by the provider for low cost long distance calls. Callback service is available anywhere in the world.
And here are the other perks:
By using Callback you will reduce your phone bill with 60-80%
The prompts are in more than 10 different languages
It's remote programmable capability allows you to use the service even while traveling
You can receive information about your current bill via email
The service might be used by a computer or a mobile phone. You do need an Internet connection. If you have one the only thing you need to do is dial the access / trigger number given to you by the service provider. There are several numbers you might dial. First, there is the 'Standard trigger number' used for receiving calls if your location is permanent. However, there is the 'Traveler Trigger Number' which allows you to receive calls even if you change your location. But that's not all because you also get a 'Personalized Trigger Number' which uses the user's name to connect and is also based on a permanent location.
With Callback you get a variety of options so if some of them fits your needs, just try it yourself and enjoy making cheap international calls to every country in the world.