Recently i was wondering if it is possible for people to evesdrop on my telephonic coversations.

I was taught that GSM is quite secure. But since i heard a lot about mobile phone tapping cases in the news i was quite curious to know how this thing works!
whats the mechanism behind it! how do those GSM towers, signals etc. work?
How do they do it?

- one more thing, if you use Nokia and turn "Cell info display" on. the cellphone screen shows the current location of the mobile phone. Right?
How does it do that? and can any unethical guy by using some technique get information about that location of mine?


HOW CAN I PROTECT MYSELF?