Skype began the internet telephone calling revolution. You can call free worldwide. Just as useful is the ability to make calls to mobiles at local rates abroad. You can also 'screen share' which can be great for training. Group calling is also free now.
You do need a good internet connection at both ends for clear conversations! If you start to breakup try turning your video off avoiding moving too much as this reduces the processing load on your computer. You will also get better results with faster computers as all the processing is done locally rather than on internet servers. Business level services all work on these servers and so work better poor internet connections.