From Novice To a Masterpiece.

The way the Cell Phone works

Introduction
We guys, and gals of course, take everything for granted these days. Buy a new computer, just load it with whatever software we get, use them blindly. Buy a music system, get all the CDs in the world, listen to them and so on. If we are slightly inquisitive about their anatomy and try to find out as to how they function, I think we will be able to use them better than our counterparts. This theory, call it Sandeep's Theory from now on if you like, holds good for anything, repeat anything. Be it your pocket shaver or your cell phone. Ah! I just remembered; here's a brief writeup on how a Cell Phone works. Compared to the other articles this is a brief one.
First things first. A cell phone does not have any wires. So whatz za big deal, you say. There is one. In normal telephone excange systems, a pair of wires connects each of the instruments to the exchange. The wires are usually made of copper. When a handset is lifted, an indication called a loop is sent with the help of these copper wires. In some countries, however, Optical Fibers are used. These wires are noise resistant and hence improve efficiency and speed.
The Connection

When you dial a number, the signal is sent to your exchange in the form of pulses. The exchange now tries to establish a connection with the guy with whom you want to gossip. This is the duration wherein you hear the ignoble beeps. Once established, you will be able to yap as long as you wish. The exchange which tries to establish a connection is called the Originating Exchange ( in this case, the former). And the exchange which is requested for a connection is called the Terminating Exchange (in this case, the latter). During your conversation the communication path is used to send signals in bits.
The conversation begins only after the data sent by the originating exchange is received by the terminating exchange, analysed, and sent back to the originating exchange, indicating that the line is clear .
In the Cell Phone system, since there is no wire connection, the connection is established between the caller an the receiver thru an intermediate station called the Base Station(BS). This station consists of transmitting towers. The BS is connected to the mobile exchange thru wires. You are connected to mobile exchange thru a Radio Channel. Of course, there are innumerable exchanges and these are connected by wires.
Operation Research

How about giving your cellphone a whacky name? Well, it is called as a Mobile Station(MS). Your mobile exchange is called as the Mobile Switching Centre (MSC).
The term cell comes from the fact that an area is divided into a number of cells. You exist in one cell, and your friend may exist in another. Assume that you belong to cell A which is just one of the umpteen number of cells of the region S. The strength of the signals will be maximum and the clarity, very high, if you are inside your cell, while speaking. Say you are in a vehicle while you are speaking and you cross your cell. Even then the connection is not cut. Why? Read On.
Crossing Limits

When you go out of the boundary, you will be entering another cell, say cell B. This is detected by cell A and the BS reports to the MSC indicating that you have left the cell and that your signals are becoming weak. Now, the MSC orders the ohter BSs to detect a newcomer. Obviously, the BS of B detects a newcomer. It sends a report to the MSC indicating that a newcomer is present. The MSC orders the BS of A to hand you over to the BS of B. This is technically called as Handing Off. This process is done in a mere 500 milliseconds or even less. Thus while you move from one cell to another the maximum disturbance that you will hear is...Nil.
SIM Cards
Each cell phone is associated with a unique identity, a finger print if you like, which is stored in the Subscriber Identity Module. This is a card. When you press the SEND button on your handset, this code is sent to the MSC thru your BS. If you are an authorised user, which is decided by the MSC after it analyses your code, you will be allowed to communicate.
If there's an incoming call to the MS, first it is received by the MSC, analysed and the called number is paged in all cells. If the MS is kept powered on, a page response is received on the control channel from the MS. A voice channel is allocated by the MSC. BS and MS are ordered to tune to that channel. Once tuned thru connection, the info is sent to the caller who gets a ring-back tone. Ringing is initiated in the MS. When the MS answers, conversation can start and metering starts in the MSC.
Concluding Remarks

Now, you know the Behind the Scenes action. So much of work is done without your knowledge. So many Hand-Offs, so much of information transfered. Everything goes unnoticed. Remove one entity from the list and your conversation comes to a standstill. I hope the information which I have provided is just enough for a normal user.
Though I have said that there's no noise during hand-offs, it is not the case always. It is better to be confined to your cell if you never want to have any disturbance. Also, use your handsets as less as possible. This advice is not with the view that you save money, but with the fact in mind that, the signals thoroughly affect your brain. The damage is maximum when you are trying to make a call. Be careful,please.
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