|By: Erin Becker|
However, have you ever actually wondered how it is that a cellular phone call is made, without any wires or visible connections? They are actually pretty amazing devices; especially considering the fact that they are essentially sophisticated radios.
A cell phone is - put simply - a kind of two-way radio that acts in the same way as a telephone. However, naturally a cellular phone is much more complex than a simple walkie talkie, as cell phones permit two people to speak at the same time, making calls and receiving calls, three-way calls, call holding, voice mail, text messaging, etc.
However, similar to walkie talkies, all mobile phone calls are entirely unprotected and can be intercepted by other devices. Cell phones aren't at all as "secure" as wired telephones. They have the same security level as a radio - which, after all, they are.
When you place a cellular phone call, you dial the number and press the send button. A number of steps then follow:
&bullYour cell phone scans for the nearest base station in order to provide it with the strongest signal and, in turn, the best possible connection. It checks 21 different control channels to determine the strongest available signal.
&bullYour cell phone then selects the strongest signal for its use.
&bullAn origination message (a very short message of about ¼ second in length) is then sent by the cellular phone, which includes its MIN (Mobile Identification Number, that is, your cellular phone number), as well as the ESN (Electronic Serial Number), and the number that has been dialed.
&bullOnce the cellular service provider verifies that you are among its customers - based on the sent-out MIN and ESN - the base station sends a channel assignment message to the cellular phone (another ¼ of a second in length), telling the phone where the conversation will be.
&bull The cell phone then tunes into that assigned channel and the call begins.
All of this has happened by the time you hear the ringing or busy signal on the other end of the phone.