If you search this forum for telna you will find a few people mentioning that they use them. Even if you were not heading out internationally, they are one of the better pay as you go plans out there at eight cents a minute for time used.
They did not have free incoming in the places I would be using the card most, so to me it didn't make sense as most of my calls are incoming. If my usage was in other areas it probably would have made some sense and I keep saying I need to give them a try at some point.
They also offer their customers a $49 quad band phone if needed.