Cell phones
You turn off your cell phone when you board an airplane in one city, and you turn it back on in another city. Your phone rings. How does the cell phone company track you down and deliver your phone call to your cell phone?
posted by Pedicularis @ 2:52 PM
6 Comments:
Magic.
they are stalking you ped!
I was trying to find out if anyone knows. I don't know exactly how they do it, but here is a method I think would work: Whenever your cell phone is up and running, it occasionally emits a "I am here" message, very short, just text, with its cell phone number included. This takes power, by the way. Any cell tower that hears the "I am here" signal decodes your cell phone number and sends a message to "your" server that gives the identification of the cell tower that heard your "I am here" message. "Your" server probably has a database of the current cell towers within range of all of the cell phones in your area code. Your server (which could be anywhere but probably resides within your area code for efficiency) must also keep all your missed calls and messages. If you have some, then your server will then send a message back to the cell towers who heard your cell phone's "I am here" message, which are then broadcast for your cell phone to hear. If your cell phone receives this broadcast, it alerts you. This all could happen within a minute.
I think you've got it.
A cell phone sends out signals when it's on, to the network. The network holds messages until the signal from that phone (sim cards specific signal) is received. If myself and a friend took our phones from the UK, and went to the states, and then tried to phone each other we would have to pay for the signal to go from the states to UK and back to the states! OUCH expensive roaming fees!
I do wonder how long a message can be held by the network?!
BTW, how should I be pronouncing "Iccle Anne"? When I see your name, I pronounce it "Icicle Annie", but I have added two "i's".
It should be "ickle" (as in tickle)...I'm short and "iccle". It's a made up word, can't remember who came up with the spelling, but it's stuck. It was a cute nickname, the only one that I've liked. I can understand why the icicle confusion though.
Anne is said the same as "Ann", it's just spelt with an e. Not a fan of Annie, rhymes with much more insulting words than Anne/Ann!
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