How do Mobile Phone Calls Work?

How mobile makes a call?

For most folks, a mobile may be a part of our lives. But I’m sure your curious minds have always been struck by questions like how do mobile phone calls work?

So during this article, we discuss “How mobile makes a call”, and “Reasons for various generations of mobile communications?”

How do mobile phone Calls work?

Let’s explore the technology behind mobile communications.

mobile phone calls working
When you speak on your phone, your voice is picked up by your phone’s microphone. The microphone turns your voice into a digital signal with the assistance of the MEMS sensor and IC.

The digital signal contains your voice within the sort of zeros and ones. An antenna inside the phone receives these zeros and ones and transmits them within the sort of electromagnetic waves.

Electromagnetic waves transmit the zeros and ones by altering the wave characteristics, like the amplitude, frequency, phase, or combinations of those.

For example, within the case of frequency, zero and one are transmitted by using low and high frequencies respectively.

So, if you’ll find how to transmit these electromagnetic waves to your friend’s phone, you’d be ready to establish a call.

However, electromagnetic waves are incapable of traveling long distances. They lose their strength thanks to the presence of physical objects, electrical equipment, and a few environmental factors.

In fact, if there have been no such issues, even then, electromagnetic waves wouldn’t keep it up forever, thanks to the Earth’s curved structure.

To overcome these issues, cell towers were introduced, using the concept of cellular technology.

In cellular technology, a geographical area is split into hexagonal cells with each cell having its own tower and frequency slot.

Generally, these cell towers are connected through wires, or more specifically, glass fiber cables.

This glass fiber cables are laid under the bottom of the ocean, to supply national or international connectivity.

The electromagnetic waves produced by your phone are picked up by the tower in your cell and convert them into high-frequency light pulses.

These light pulses are carried to the bottom transceiver box, located at the bottom of the tower for further signal processing.

After processing, your voice signal is routed towards the destination tower. Upon receiving the pulses, the destination tower radiates it outwards within the sort of electromagnetic waves, and your friend’s phone then receives the signal.

This signal undergoes a reverse process, and your friend hears your voice. So, it’s true that mobile communications aren’t entirely wireless, they are doing use a wired medium too.

This is how mobile communications are administered. However, there was an enormous issue that we intentionally left unanswered.

Mobile communication is merely successful when your tower transfers the signal to your friend’s tower.

But how does your tower know during which cell tower area your friend is located? For this process, the cell tower gets help from something called a Mobile Switching Center.

Also, read about Cell phone tower radiation really affects humans? here

mobile phone calls working block diagram

Mobile Switching Center (MSC):

The MSC is the central point of a gaggle of cell towers. Before moving further, let’s explain more information about MSC.

When you purchase a SIM card, all the subscription information is registered during a specified MSC.

This MSC is going to be your home MSC. the house MSC stores are information like service plans, your current location, and your activity status.

If you progress outside the range of your home MSC, the new MSC, which serves you instead, is understood as a far off MSC.

As you enter a far off MSC region, it communicates together with your home MSC. In short, your home MSC always knows which MSC area you’re in.

To understand during which cell location the subscriber is within the MSE area, the MSC uses a couple of techniques.

One way is to update the subscriber location after a particular period. When the phone crosses a predefined number of towers, the situation update is again done.

The last one among these is when the phone is turned on. Let’s attempt to understand all of those procedures with an example.

phone calls working

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Real-Life Example:

For example, Emma wants to call John. When Emma dials John’s number, the decision request arrives at Emma’s home MSC.

Upon receiving John’s number, the request is going to be forwarded to John’s home MSC. Now, John’s MSC checks for his current MSC.

If John is in his home MSC, the decision requests are going to be immediately sent to his current cell location, and it checks whether John is working on another call, or if his mobile is transitioned.

If everything is positive, John’s phone rings, and therefore the call is going to be connected. However, if John isn’t in his home MSC, John’s home MSC simply forwards the decision request to the foreign MSC.

The foreign MSC will follow the previously explained procedure to locate John’s phone, and can then establish the decision.

Now, let’s discuss why the frequency spectrum is sort of important in mobile communications.

To transfer zeros and ones in data communication, each subscriber is allocated a frequency range.

However, the frequency spectrum available for cellular communications is sort of limited, and there are billions of subscribers.

This issue is solved with the assistance of two technologies, one frequency slot distribution, and two, multiple access techniques.

In the 1st technique, different frequency slots are carefully allocated to different cell towers.

In the multiple access technique, this frequency slot is efficiently distributed amongst all the active users within the cell area.

Also, read about Sensors used in smartphones here

Now, the large question. Why are there different types of mobile technologies?

Generations of mobile Technologies:

1st Generation(1G):

1G originally allowed users, for the primary time, to hold a phone without a cable attached thereto.

But 1G suffered from two major problems. the primary problem was that the wireless transmission was in an analog format.

Analog signals that are easily altered by external sources. So, it provided poor voice quality and poor security.

The second problem was that it used the frequency division multiple access techniques, which used the available spectrum in an inefficient way.

2nd Generation(2G):

These factors paved the way for the second generation of mobile communications, 2G used digital multiple access technologies, namely TDMA, or CDMA technology.

The second generation of mobile technology also introduced a revolutionary data service, SMS, and internet browsing.

3rd Generation(3G):

3G technology was focused on giving better data transfer speed. It used a WCD multiple access techniques, alongside a rise in bandwidth.

To achieve this, the 3G speed of two Mbps allowed the transfer of knowledge for uses like GPS, videos, voice calls, et cetera.

3G was an enormous step within the transformation of the essential phone to a smartphone.

4th Generation(4G):

Next came 4G, which achieved speeds of 20 to 100 Mbps. This was suitable for high-resolution movies and tv.

This higher speed was made possible thanks to the OFD multiple access technologies, and MIMO technology.

MIMO uses multiple transmitter-receiver antennas inside both the mobile and therefore the towers.

5th Generation(5G):

The next generation of mobile communication, 5G, to be unrolled soon, will use enhanced MIMO technology and millimeter waves.

It will provide seamless connectivity to support the web of things, like driverless cars and smart homes.


I hope you can get some knowledge about how do mobile phone calls work? by reading this article.


Hey, if you want to give any suggestions to the Tech Geek, then comment down below.

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