How does communication takes place in a mobile phone?

This are the steps

1.Identifying the number:

All the numbers you dial in have a specific frequency this you wont realize if you are using smartphones because in them they are masked as it is considered a security threat to experience them take an phone of a physical keyboard make and press all the buttons you will soon realize that every number you type in makes a different sound than other.

So in practical case as you are typing inn the numbers this frequencies are identified and the call made.

2.Identifying the receiver:

All the cellphone numbers are unique and the first few numbers you type in are company specific like 9819 in Vodafone, thus identifying the service provider of the recipient of the call. While the rest of the numbers distinctly identify the user.

3.Connecting the call:

There is a slight gap to you dialing the number and the ringer starting this time is spent in sending a ping between two ends to see that the channel is connected while parallely identifying users at both ends so that their tariff plans are identified from the database and they can be billed accordingly and provided services accordingly too.

4.Keeping the conversation on:

Now this is a little technical but i will try my best to simplify it. In this processes your speech is received converted into equivalent electrical signals, modulated and then sent across the channel to other user's device where his device will interpret the data accordingly. How it is done involves lot of methods and systems and via's and there is a subject regarding the same just google it if you are interested in studying it is vast.

5.Ending the call:

This is pretty straightforward the system waits for either user to press the end button as soon as you do that again it is a game of frequency, the system only one user to press the end button to end the conversation. There are other parameters too like your plan and balance and other system so when you are chatting over the phone there are a set of complex system and networks which keep it going without interruption.