I'm not too surprised some reporter finally got an angle on this story and published it. The technology isn't exactly new or anything like that.
I remember back in the late 80's when I was programming against some PBX switches we could listen in to peoples private conversations without them (anyone) actually using the phone. Audix and Nortel codes were easy to manipulate and you could do some fun stuff. I actually reprogrammed one guys phone to forward his messages to the boss while he was away on vacation. We also used to ring down to other floors and use the speaker to talk "This is god! I know what you're doing and you'll go to hell for sure if you don't stop."
Now this was way back in 1988 and 1991. Just think how far listening in to private conversations has come since then?
P.S. I worked as a database programmer for a small telecom and one of the largest, so I know just enough to have fun.
Here's another one. Don't trust your voice messages because almost every machine I've ever encountered is easy to hack and listen to the messages. Hmmmm....
Cheers, and don't panic...too much!