Can I use a phone card to call from skype?

I used a phone card before to call from skype, and I ran out of minutes, today i bought 2 cards, both are different providers, and for some reason when I cann the 1800 # for the card, both cards, the number is busy....when I call from a landline phone they are never busy..... anyone know why, or know a way around this, or even a way I can make calls from my compuer useing phone cards I purchased?

Can I use a phone card to call from skype?
What can I say to you? Read a calling instruction carefully. And you can make calls from your computer if your phone cards have a PC-to-phone option. For details visit International Phone Card Review