I know Private investigators have a source they use, but I have never found one that was free. I have also heard that the results with Intelius vary and are not always accurate so you might want to be cautious. 

I've read that Intellus does not really do much beyond provider and location.
I found a free service, http://phonetrace.org/ (PG-13)

I remember finding a ring tone download website which would tell you the carrier, but then you'd have to call and SE more details.

The only other option I found is to spoof the cell phone number and call a landline for the caller ID info... but that suggestion would better be posted and discussed at http://www.unethicalhacker.net (yours for the low price of $450) run by Evil Don and such illustrious posters as Evil Unsupported, Evil Hayabusa, Evil BillV, Evil Ketchup, Evil Jhaddix, Evil ZeroFlaw, etc. (who look just like their normal counterparts, but with goatees).

Wow!  I now have an alter-ego on the dark side.  Yes !!!  Now have to work with those named individuals to create our own mini ethical hacker league of heros!

<kidding>  But that was one of the best replies I've seen on any board, all week.  Well done!

Does that mean the good chrisj has a goatee/beard, or are you just trying to trick the rest of the evil alter egos?

I've been sporting a beard / goatee for 10 years now. I have it off once a year or so for some Social Engineering, but that's about it.

When someone sees a ninja in the office, it's kind of like a buffer overflow for the brain. It's a little overkill for a Social Engineering attack, but effective nonetheless. Whatever works, right? 

Don

What's an afternoon cup of coffee???  <kidding> but I could sure use one, right about now.

Ketchup, I'd love to see the ninja dropping from the ceiling bit.  While everyone was staring at you, I'd be doing all kind of info gathering in the background...  Nothing like some 'reverse' social engineering, that is, relying on someone else's social engineering activities to do all the attention grabbing, while you casually grab what you need.   

Why do the work if someone else will do it for you, right???  <chuckle>