I have been using Skype forever now. It was my only tool for another job assignment I previously had. I don't understand why some people have issues with it - It was reliable all the time for our team calls, file transfers, screen sharing, and so on...
Having all that for free puts you closer to your team members and boosts your efforts to train and motivate.
To me Skype is Very effective, and I have not found a better one yet.
I hope that answers your question.
