Wire taping and spying question?

So with all the buzz of wire taping lately regarding the NSA I have started to look into how to wire tap and how to discover it. I have found that Skype is by far the most secure form of communication, atleast skype to skype. But what I am curious about is skype to mobile phones being intercepted, since I make many calls like this to a foreign country that probably drives the NSA mad. Though my main concern is not the American goverment as much as it is hers. Either way, First I would like to know how easy it is for Mobile to Mobile to be wiretapped, and second what do you think about Skype to Mobile? It is my understanding that Mobile to Mobile is pretty difficult to intercept, however tracking its location is simple. What does the collective have to say about this?