I hate the fact that they deem this "hacking"..Most peoples concept of hacking is phone bugging and listening in on convos.. Which it is far from.. This is simply going onto the remote answerphone number, putting in the default pin as most people cba to change it and boom your in..
On a side note again, to listen in on a phone conversation on a mobile network is epically hard, the equipment needed to crack the algorithms are pretty awesome. Its not like the old tapping of the line with analog signals...