You usually can turn it off I think. One of my colleagues' greeting states that you should _not_ leave a message, followed by 2 minutes of silence, to put off all but the most committed.
> [A]n identifiable natural person is one who can be identified, directly or indirectly, in particular by reference to an identifier such as a name, an identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person.
I think the principle is that since an IP address could be used to identify you, it is considered personal data.