| It seems that just about everybody these days | | | | number and press the send button. A number of |
| has a cellular phone. In fact every day there are | | | | steps then follow: |
| approximately 100,000 people around the world | | | | • Your cell phone scans for the nearest base |
| signing up for a new cellular phone service. | | | | station in order to provide it with the strongest |
| Therefore, it is easy to say that the cell phone is | | | | signal and, in turn, the best possible connection. It |
| becoming one of the most important devices of | | | | checks 21 different control channels to determine |
| our time. | | | | the strongest available signal. |
| However, have you ever actually wondered how | | | | • Your cell phone then selects the strongest |
| it is that a cellular phone call is made, without any | | | | signal for its use. |
| wires or visible connections? They are actually | | | | • An origination message (a very short |
| pretty amazing devices; especially considering the | | | | message of about ¼ second in length) is then |
| fact that they are essentially sophisticated radios. | | | | sent by the cellular phone, which includes its MIN |
| A cell phone is – put simply – a kind of | | | | (Mobile Identification Number, that is, your cellular |
| two-way radio that acts in the same way as a | | | | phone number), as well as the ESN (Electronic |
| telephone. However, naturally a cellular phone is | | | | Serial Number), and the number that has been |
| much more complex than a simple walkie talkie, | | | | dialed. |
| as cell phones permit two people to speak at the | | | | • Once the cellular service provider verifies |
| same time, making calls and receiving calls, | | | | that you are among its customers – based on |
| three-way calls, call holding, voice mail, text | | | | the sent-out MIN and ESN – the base station |
| messaging, etc. | | | | sends a channel assignment message to the |
| However, similar to walkie talkies, all mobile phone | | | | cellular phone (another ¼ of a second in length), |
| calls are entirely unprotected and can be | | | | telling the phone where the conversation will be. |
| intercepted by other devices. Cell phones | | | | • The cell phone then tunes into that assigned |
| aren’t at all as “secure” as wired | | | | channel and the call begins. |
| telephones. They have the same security level as | | | | All of this has happened by the time you hear the |
| a radio – which, after all, they are. | | | | ringing or busy signal on the other end of the |
| When you place a cellular phone call, you dial the | | | | phone. |