minor related reference from crypto list posting
http://www.garlic.com/~lynn/aadsm23.htm#38 NSA knows who you've called

there was some recent announcement (I forget where I saw it)that somewhere they are going to start sending location specific advertisements to your cellphone ... as you move from place to place ... they will transmit advertisements to your cellphone that are specific to your current physical location.

I have probably missed something: What is the issue with zero-length SMS message? Do towers use this approach to detect a phone presence/location?

Interesting article anyway, thanks!

I've adjusted the article a bit - there is an acknowledge bit that needs to be set, that results in your phone sending back an ACK that you don't know about. This is uncharged, but it pops up in the records.

These days the phones themselves are so cheap that they can perhaps be used disposably for these purposes.

I got a good learning but somewhere i felt that still we have to go up in this techniques.
And suppose,i m talking to somebody on his/her mobile phone and at the same time i want to trace his/her entire information. ( like address and all etc.)
how can we do that?