MELISSA BLOCK, host:
So how does the phone company keep track of your phone calls, and what types of calls are tracked? To answer those questions, we called Carol Wilson, editor-at-large for Telephony Magazine.
Ms. CAROL WILSON (Telephony Magazine): Today, the telephone companies operate at the core of their network using something called Signaling System 7. And what happens when you make a long distance call, when you actually lift your handset off your phone, a signal goes out in a little separate data path, very high speed data path through the network, and as you enter the digits that all goes to the network to determine whether or not the phone number you are calling is reachable, whether you called the right number, whether somebody's busy. And all of that happens in milliseconds.
And that's one of the reasons why this Signaling System 7 was implemented, so that phone companies can make more efficient use of their networks. But what happens along the way, once you're created this little out-of-band signaling path, is it enables the network to then do all kinds of things with database dips where, for example, when you call from New York to Los Angeles, the network can very quickly determine that the person in Los Angeles has paid for Caller I.D. and it will deliver not just the telephone call, but it will deliver first the Caller I.D. record, the name and the number.
BLOCK: Now, as these calls are made, records are generated, too. What's kept in those records for long distance calls?
Ms. WILSON: Very basic information, the originating phone number, the terminating phone number, the date and time of the call and the duration of the call.
BLOCK: And is that information traveling in some way on a parallel path to the call itself?
Ms. WILSON: Well, the separate little data path where the information travels in milliseconds is, again, it's an out-of-band signal so it's not on the same exact path as the phone call, but the information itself, where those kinds of records are stored, that's going to be in an operation support system of a telephone company, used for billing and that kind of thing.
BLOCK: And is that pretty much what they use it for, billing? What else might they want that information for?
Ms. WILSON: Primarily it's for billing. They're also going to be doing in some cases their own data mining to determine what they call busy hour call volumes where, for example, there might be congestion in the network. Traffic patterns to help them determine where the network needs to be upgraded. But for the most part, it's routine billing information.
They do turn over that information on a routine basis under subpoena and in accordance with what the letter of the law is for turning over information to law enforcement officials.
BLOCK: What about with local calls? What kinds of records are kept there?
Ms. WILSON: Well, in many areas where local service isn't measured service, where it's an unlimited service, they don't really track how long you talk or who you're calling, for that matter. Once they've delivered the information they need to deliver, they don't track that and they don't store it. In some areas, for example I live in Chicago and here AT&T is our local service provider. It does provide local measured service and so they are tracking who you're calling in order to measure the distance and bill you accordingly.
BLOCK: I wonder, hypothetically, and this is purely hypothetical, but the companies are gathering this data about the phone calls. Not the content of the phone calls. How difficult would it be to go from collecting the data of whom was called and for how long to collecting the content of that call?
Ms. WILSON: It would be dramatically different. It would be a whole different technology. At this point, they do provide law enforcement officials with the opportunity to wiretap and they have to maintain that ability for law enforcement, but those wiretaps are done under court order.
It's a very, very different thing. As I said, the data about the call travels on a whole separate path of the network. It's a very different thing than if you start collecting what people are actually saying on the phone call. It's a different technology, and it would be implemented in a very different way.
BLOCK: Carol Wilson is editor-at-large for Telephony Magazine. She spoke with us from Chicago. Carol, thanks very much.
Ms. WILSON: You're welcome.