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Mi Max 2

[Discussion] [How it Works #3] What happens inside your smartphone during a phone call?!

2019-04-22 01:33:46
992 41

Dear Mi Fans!
In this article, we'll talk about - What happens inside your smartphone during a phone call !? I think everyone will be interested.
Once you get the smartphone out of your pocket, it's in standby mode! The central processor and all the other components supporting its work at this time consume very little charge.Completely disconnected from the power is only the screen, when you press the unlock button on your smartphone - the power circuit inside the button. The power button and the volume control buttons are controlled by separate chips.

The chip catches the change in the power circuit and sends a signal to the CPU. The CPU captures the changes and instructs the screen to turn on. The electric current is fed to the motherboard of the power controller, it increases the current and voltage on the motherboard tracks going to the components including the screen.

The signal from the processor does not go directly to the matrix, it first goes to the decoder

This microchip attached to the display translating the processor commands to include specific pixels on the matrix light up the pixels consisting of red, green and blue colors

These colors blend and create an image on the screen. The menu for unlocking the screens is displayed, the finger touches the screen for entering the pin code. Each touch is recognized by a grid of the touchscreen.   It is always under a small voltage, the touch does not interrupt the power circuit

the finger works like a plate of the electric capacitor .

At the moment of contact, the forces of the flowing currents in a certain sector change by changing the voltage, touch determines the coordinates of the tangency along the X and Y axes.

Sends data to the processor which in turn fixes them and based on the firmware algorithms, instructs the screen to render the animation of the clicks to the virtual buttons.

The entered pin-code is compared with the database to special security algorithms, if the PIN code is entered correctly, the smartphone is unlocked.
Animation of desktops is drawn, a lot of sleeping processes are started for the correct operation of the operating system. The smartphone enters the active mode. You start the application to make calls,  by pressing the green button on the screen. At this time, the processor loads it into RAM,  at the same time drawing the application interface, contacts and a record of all previous calls are downloaded from the permanent memory. You simply dial a number or select a contact from the list, press the call button and wait a few seconds before the long beeps appear.Lifting the phone to your ear, you cover the beam of light coming from the distance sensor.

It determines the distance from the smartphone to the ear and transfers data to the processor, which in turn commands to turn off the screen backlight.

The radio module or modem communicates with the network immediately after the smartphone is switched on for registration in the network, the radio module is always active and periodically communicates with the network of the mobile network operator.

Identifies you as a subscriber using the SIM card.

A small voltage is applied to it through special contacts, it suffices to work inside the sim card of its own microprocessor of operative and permanent memory and even a small set of programs.

Operator data such as:
  • information balance;
  • the rest of the traffic;
  • data trafick;
  • NOT stored on the SIM card !!

The memory is needed for storing encryption keys and its own number, and which in the operator database is ssociated with the phone number. In the additional memory of the sim-card can be stored contacts, sms and a phone number - but this is alread obsolete methods and now they are practically not used !At this very time, the radio module sends a signal to the antenna of the smartphone. The signal is picked up and transmitted to the antenna of the nearest base station, with the help of which the telephone sends a request to connect with your friend, as well as his number.

The network itself knows your number in advance and sends it to your friend so that he knows who is calling him. The base station most often looks like a red and white tower.

In the city they are hidden on the roofs of houses.

The base station sends a request to the BSC, and the controller forwards it to the MSC switch, it checks against the HLS and finds out where the called subscriber is at the moment. Transfers the call to the appropriate switch, and from there to the controller and then to the base station located in the reach zone of the subscriber at the other end.

The base station sends a signal to your friend's smartphone that catches it with its antenna and converts into an electrical pulse the radio module that is fed to the radio, it notifies the processor of an incoming call.

The processor starts the programmed algorithm, activating the menu and the ring mode.

The screen with the number of the incoming call lights up. The voltage is applied to the eccentric - it's a small electric motor known as a "vibrator", on the axis of the motor the cylinder is set crooked and dangles during rotation.

During rotation, vibration is created and the phone creates a buzzing effect. The electric current from the battery is also applied to external speakers. The audio processor converts the digital signal of the audio track into an analog pulse, which causes the speaker membrane to vibrate creating a ringing tone.

The subscriber picked up the receiver by clicking on the green icon on the screen and said "Hello"at this time the microphone caught the sound and converted it into an electric.

The pulse is transmitted to the radio module, this sends it back to the base station antenna.

There was a connection between two subscribers located at a great distance from each other. Thanks to the development of technology, we have learned to transmit simultaneously signals from two phones - both on reception and on return. We invented the most complicated algorithms of program code and hardware components from hundreds of the smallest elements, so that each person had the opportunity to say the most important words to their loved ones and friends at a distance of hundreds of kilometers.  

In order for important information to be transmitted instantaneously to colleagues and business partners, due to mobile communication, technical progress is not limited to the time needed to respond to the letter, we no longer need a personal visit to transmit important information.
Roman civilization has become so great - thanks to the roads connecting cities for the transfer of valuable goods and information. But a mental connection with any person today is an excellent tool to build the greatest civilization, and a smartphone as a symbol of our era is an excellent proof of the victory of reason and technology.

Thanks for your time!
Special thanks to all mods, Smods and Admin!


Number of participants 7 Experience +51 Pack Reason

View Rating Log

2019-04-22 01:33:46
Favorites24 RateRate
This is one of the best articles that explains in detail the simple processes that occur in our smartphone. Thanks 4 ur work!
2019-04-22 01:50:47

Device team

$huvo | from Redmi 4


Informative thread for us
2019-04-22 04:20:55

Master Bunny

Md. Lutfor Rahman | from Redmi Note 4


Holly cow! I didn't know that!
2019-04-22 04:33:59
Md. Lutfor Rahman
Professional Electronics and Electrical Engineer


Doellah3 | from Redmi Note 7


thanks for your time to make this article..awesome. i like it. :)
2019-04-22 05:11:39

Grand Master Bunny

Ratpenat | from MI 5s


Excellent Info, thanks
2019-04-22 08:55:48

Pro Bunny

myrichgoh | from MI 8


Thanks for sharing.
2019-04-22 09:25:57

Rookie Bunny

1700574558 | from Redmi Note 4


Thanks for this explanation very usefull
2019-04-22 11:35:12

Beta Team-China

Dorarch | from MI MAX 3


Informative thanks
2019-04-22 14:02:03

Resource Team

BeingBishal | from MI 5


Nice Information!
2019-04-22 14:02:22

Master Bunny

Murshad | from Mi Note 3


Very much detailed
2019-04-22 22:59:51
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