What's it take to trace a phone number these days?

A while ago, I was watching the cinematic masterpiece that is Die Hard: With a Vengeance, and it made me think of something.  But then I forgot what it was.  Gripping tale so far, right?

Last week, I watched an episode of Fringe (I am not a fan of Fringe, but it's something that I can watch while not paying attention) and an episode of The Mentalist and it brought back all those memories about what it was that I forgot that I was wondering about earlier.

What does it take to trace a phone call these days?

There's always a guy with a metal briefcase filled with what I suspect are an oscilloscope, a few knobs and switches, and a map.  But we live in a world of caller ID and Google.  Reverse phone number searches are practically routine - I do them whenever we get a number that we don't recognize.  And while I'm usually only able to get the city that the number is from (and yes, I know that this can be spoofed), how much harder can it be to get the address?

In all shows and movies, there's always a suspenseful scene in which the Phone Call Trace Technician says "Keep him on the line as long as possible."  Therein follows a back and forth between the kidnapper/terrorist/thief/murderer/telemarketing victim during which we cut back and forth on the banter between the callers and the PCTT who says things like "thirty more seconds" and "ten more seconds" and "no good, we lost him". 

Ultimately, phone tracing never works and when it does it's only as a red herring.  The police/FBI/CIA/KGB/Tom Cruise break down the door of the suspect backed up by most of the military forces of whatever country it's happening in, only to discover that the phone line was jimmied (I don't get to use the word 'jimmied' a lot, and I'm not sure I've used it properly here, but I feel I deserve credit for getting it in) and the real criminals are laughing at them through telephoto lenses set up on the other side of the street and streaming the video to their underground lair/space station/website offering hot live police action 24 hours a day XXX.  

I have a theory. 

Tracing phones probably doesn't take any time at all. I'm betting that if the authorities ever did need to trace back a phone call, it could be done in a matter of moments - even while the call was ringing.  I think that the reason that the whole "phone trace scene" is always played out like it is is because they don't want us to know this.  That they would prefer that criminals think that they have sixty seconds before they have to hang up or get caught. 

Oh, did I mention that I also watched Conspiracy Theory too?  It's a good movie.