I've used it often while traveling. It works well and it is free as long as you are calling another computer. They have a very low per minute charge if you are calling a land line.
It's a good idead to pick up a cheap set of headphones witha mike to make the actual calls. I travel with these:
http://www.plantronics.com/north_ame...032/prod440042
as they are folable and go in my laptop bag. At home we use these
http://www.plantronics.com/north_ame...true&mftr= which are cheaper but not as portable.