I started to use skype just three months ago. It worked very well but since i started to use video calls there were issues one after the other. Now I have decided to dump my video call obsession. I could not get my skype service back on track despite all my struggle. Now a day, I am looking for some service like packet 8 axvoice etc. that I can use on my phone set.
As far as the skype free service is concerned, it is not very reliable. I would advise you to spend some money and get better service from some "real" voip service provider.