Sim card in multiple break off cases

What is a Sim card?

A sim card simply means Subscriber-Identity-Module or Subscriber-Identification-Module.

It is used to access connectivity to the telecommunications network for the communication services they provide.

Sim cards give us the ability to make and receive phone calls and SMS (Short Message Service), connect to data, and other value-added services.

Users can subscribe to the providers network either by Contract (post-paid services that you use and pay later) or by Prepaid (pay for subscription services or airtime before use).

Most sim cards are small and rectangular-shaped plastic cards.

These cards are engraved with technically readable chips called Integrated circuits (IC).

Although with current innovations, we now have virtual and embedded sims (eSim).

The IC is a small break-away surface area that is located at the top right corner of the plastic card.

The IC is the component that enables the sim to connect to a network, without it, the sim will have no network connection.

Every sim card has a unique Integrated Circuit Card Identifier (ICCID) and International Mobile Subscriber Identity (IMSI) numbers.

Each user’s ICCID and IMSI have a unique usage and ownership validity set just for the period during which the sim card is theirs. This means your sim card numbers are unique to only you.

If you stop using your sim card and it gets expired. It churns, gets re-created, and re-assigned or sold to someone else after some years.

This is one of the reasons some people will sometimes call your number and insist it belongs to someone else. Numbers get re-assigned if not in use for a long period of time as it is deemed as inactive.

Black smartphone with an open sim port, sim case and a sim card

A sim card has a Read- Only Memory (ROM), a Random- Access Memory (RAM), and an Electronically-Erasable-Programmable-Read-Only-Memory (EEPROM) of about 256kb.

The ROM, RAM, and EEPROM gives the sim card the ability to secure, identify, authenticate, store, code, and decode information.

It is what gives our devices the ability to write, send, save, and delete information.

Each network provider’s unique identifier allows allocated sim cards to recognize and select their assigned network once the sim is inserted into a device.

All Sim cards come with a Personal-Identity-Number (PIN) or Pin Code, a Personal-Unblocking-Number (PUK), and a range of services the user can access.

Serial Sim Number (SSN), European Article Number (EAN), and International Article Number (IAN) are other information that may be required in some European countries when getting a Sim card registered.

Sim card with its serial numbers

What are the features of Sim a card?

Sim cards are made up of the below characteristics:
  • Sim cards are physical or non-physical such as Plastic sim cards and embedded sims (eSim)
  • Sim cards come in different sizes and capacities
  • Sim cards have readable Integrated Circuits (IC)
  • Sim cards are made up of Universal Integrated Circuit Cards (UICC) and Integrated Circuits (IC), which are the entire sim card (both Chip and plastic)
  • Sim cards have Random- Access Memory (RAM)
  • Sim cards have Read- Only Memory (ROM)
  • Sim cards have Electronically-Erasable-Programmable-Read-Only-Memory (EEPROM)
  • Every sim card has a unique International Mobile Subscriber Identity (IMSI)
  • Each sim card has a default Personal-Identification-Number (PIN) which can be personalized by the users
  • Every sim card has a Personal-Unblocking-Key (PUK) used for unblocking a blocked PIN

What is an Integrated Circuit (IC)?

The Integrated Circuit, which is the sim card’s main component, is used for network access, user identification, authentication, memory, secure storage, phone numbers, and International Mobile Subscriber Identity (IMSI).

The IC is so important because without it, the sim card will be unreadable, and impossible to connect to any network.

In most cases, a damaged IC means a damaged sim card that can be replaced by the network provider.

Blue Sim cards or smart cards


Yes, the sim card can be called a smart card because of the capabilities of the Integrated Circuit.

Although it cannot dispense money at any bank’s ATM, it can give internet access to carry out financial transactions through fintech and traditional bank apps.

What is a Universal Integrated Circuit Card (UICC)?

The whole unit of a sim card (Plastic + microchip) is technically referred to as the Universal-Integrated-Circuit-Card (UICC).

Without the Integrated Circuit embedded in the card, it will simply be a fancy-looking plastic with zero functions.

We should not have another non-degradable plastic hurting mother earth, right?!

What is ICCID?

ICCID means Integrated Card Circuit Identifier which is the unique identifier for the micro-chip on the sim card.

It is also referred to as the primary account.

This definition is according to the recommendation of the ITU-T (International Telecommunication Union- Telecommunication Standard Sector) E.118.

Globally, an International-Circuit-Card-Identifier (ICCID) is used to identify every sim.

It is also used to identify the profiles of the eSim or any non-physical sim card.

The ICCID numbers (usually about 19 digits) can be found either written on the surface of the card or stored on the sim card.

How do I unlock my Sim card?

You can unlock your Sim card using your PIN (Personal Identification Number).

Each Sim card comes with a default PIN usually a four-digit number.

This four digit number aids the user in protecting their Sim card from others by locking and unlocking it.

Using a PIN protects and gives your sim card privacy.

The default PIN can be immediately changed to a personalized PIN whenever necessary and at different times.

This gives the user the power to protect their information and privacy from others, fraudsters, or hackers.

To change a default PIN, go to settings on the Sim card menu of your phone, select PIN then select change PIN.

The default PIN may look something like 0000 or 1111.

You can change it to your preferred personalized PIN e.g., 4231, but preferably a number that is hard for anyone else to guess but easy for you to remember.

Keep in mind that a PIN can be blocked if severally inputted wrongly.

Your phone will notify you of how many chances you have left to put in the correct PIN before it is blocked.

You will be required to put in a PUK (Personal-Unblocking-Key) to unlock the sim card.

How do I unlock my Sim card P-I-N (Personal-Identification-Number)?

You can unlock your PIN using your PUK (Personal-Unblocking-Key).

The PUK is often a much longer serial-like number used in unblocking a blocked PIN.

The PUK number can be found in the same section as your mobile number in the main pack of your sim card.

The Sim pack is your personal property and should be kept secure for this time.

Inputting the PUK correctly is very important as this is the only way you can unblock your PIN yourself.

If inputted wrongly multiple times, the PUK also gets blocked.

If your PUK is blocked, you will need to contact or visit your mobile network provider with valid information to prove the ownership and a PUK unblock request.

What is IMSI?

IMSI means International Mobile Subscriber Identity.

It is a unique serial number of about 15 digits used by your network provider in identifying your Sim card on its network.

Look at it as how mobile network operators connect phone calls to other users.

The network itself (base transceiver stations) does not identify the users by their names.

Every user is identified by their IMSI which is your International unique identity for communication as a user on any network.

In other words, the network technically uses the IMSI for operating and delivering requested services such as calls and SMS to their users.

The beginning three numbers of an IMSI are the Mobile-Country-Code (MCC), the next couple of numbers are the Mobile-Network-Code (MNC), and the last ten numbers are the Mobile Subscriber Identification Number (MSIN).

The combination of these numbers is called IMSI and differs for each country specifically because of the MCC and MNC.

Internet of things devices (IoT)

What devices do Sim Cards work in?

A good percentage of people think sim cards only work on phones, but sim cards can work on various devices and machines if they are technically compatible.

Most especially now that we are in the era of IoT (Internet of Things).

IoT is part of almost everything we use today in our daily lives.

I mean, we now live in homes with automations within smart cities, isn’t that cool?

The awesome experience of speaking to our devices or appliances and getting them to do things at our command while sometimes speaking back to us is everything!

Our sim cards come alive once inserted into the right-sized sim port of any technically compatible device such as phones, Wi-Fi routers, cameras, smart-watches, laptops, game consoles, self-driving cars, robots, home automation devices, monitoring devices, machines, and any IoT (internet of things) device.

Sim cards connects us to the world through access to subscription of desired services for our daily use.

Spherical earth smart city

Do sim cards work on GSM networks only?

In general, most Sim cards are designed for phones hence they are commonly used in telecommunications.

The highest usage for sim cards is on the GSM networks (Global-System-for-Mobile-Communication), a few CDMA (Code Division Multiple Access), and LTE (Long-Term Evolution) phones are compatible.


Any ‘physical’ sim card can be removed from a device and put into another device, reasons for this can be:

  • Sim card damage
  • Phone/ Device damage
  • A flat battery
  • An international trip that requires the use of the visiting country’s sim card without any need to buy a new phone
  • The purchase of a new phone
  • When a device is out for repairs and so on

Laptop. phone. calculator, tablet, glasses, sticky note and a cup of coffee

The ease of popping out your sim for quick use on another phone is simply a great benefit of a physical sim card.

Yippee, the transferability of the sim card saved the day!

What is Mobile Number Portability (MNP)?

Mobile number portability gives you the ability and flexibility to change your mobile number from one network provider to another within stipulated requirements.

If you are dissatisfied or prefer the services of a different network provider and choose to keep your number, then MNP makes it possible for you to do so.

Requirements for MNP may include a valid form of identification, proof of ownership, and other elements the network providers request for.

This process may take 24- 48 hours, and you can port back to your previous network provider or a different network provider if you wish to do so.

Your network provider simply decouples the card serial numbers from your mobile number and then hands it over to the new network provider.

The new network provider assigns new serial numbers and other services to your number.

You become a brand-new subscriber on a different network just like that!

Note that all bills and pending issues if any, must be reconciled before seamless Mobile Number Portability can take place.


Sim cards evolved with time due to innovation.

There are now different types, sizes, functions, and capabilities from the time it was introduced in 1991.

The advancement of mobile phone technology contributes greatly to the innovation of sim cards.

Consumer needs, and IoT (Internet of Things) in general also adds to the evolvement of sim cards.

Sim cards are made in FF (Form Factor) and are getting smaller as we advance in technology and use case.

Most phone equipment manufacturers are making smarter devices with smaller sim ports.

In recent times, the latest phones and tablets now come as one unit manufactured with eSim (embedded sims).

There are about four to five different versions of Sim cards used around the world today depending on the users’ devices.

Many different types of sim cards clustered together

How many Types of Sim cards do we have?

There are currently 5 types of functional Sims today namely: Full, Mini, Micro, Nano, and eSim.

The Full, Mini, Micro, and Nano are all physical sim cards while the eSim is a non-physical sim.

Full Sim card

Introduced in 1991 with a length of 3.37 inch x width of 2.125 inch x thickness 0.030 inch.

The full sim card came with the intimidating size of a bank credit card and is known as the 1st Form Factor (1FF) Sim card.

Most of it was plastic, engraved with the integrated circuit at the top right-hand corner.

The IC (Integrated Circuit makes the sim card functional by connecting it to the network.

Its standard reference is ISO/IEC/7810:2003, ID-1.


Mini Sim card

The mini sim card was introduced in 1996 with the 2nd Form Factor (2FF) featuring a smaller size than the full sim card.

It boasts of length 0.98 inch x width of 0.59 inch x thickness of 0.030 inch.

The functionality of the mini sim card is the same as that of the full sim.

It comes embedded in a break-away full sim casing so it can be used as a full sim or carved into a mini sim depending on the phone’s sim port.

Its standard reference is ISO/IEC/7810:2003, ID-000.                                                                               


Micro Sim card

The micro sim card came as the 3rd Form Factor (3FF), introduced in 2003.

It has a smaller size to enable it easily fit into much smaller sim ports.

The Micro sim card has the same functionalities as the full and mini sim cards.

Its length is 0.59 inch x width 0.47 inch x thickness 0.030 inch.

Though smaller in length, the micro sim’s contact area has a backward compatibility design to enable easy reading by previous and larger sim readers.

Its early users were the owners of the first iPad edition, the iPhone 4, before other smartphone owners got on it.

Its standard reference is ETSI TS 102 221 V9.0.0, Mini-UICC.


Nano Sim card

The Nano sim card is the 4th Form Factor (FF) and was introduced in 2012.

It meets the high use demand for evolving phone technology.

It has a smaller surface area, and reduced thickness but the same functionality as the previous sim cards.

Its length is 0.48 inch x width 0.35 inch x thickness 0.026 inch.

The trailblazer Nano sim user was the iPhone 5 before other smartphones.

Its standard reference is ETSI TS 102 221 V11.0.0.


eSim (Embedded Sim card)

The eSim comes directly pre-embedded in a phone or device hence its name.

It already comes programmed into the phone’s circuit board from the manufacturing stage which makes it more secure and reliable than the previous sim cards.

Since an eSim is already embedded in the device, it has no connectors nor sim ports but has a similar electrical interface for readability as the full, micro, and nano sim cards.

The eSim was introduced in 2016 with the continuous innovation of phones, Machine-to-Machine, AI (Artificial Intelligence), and other types of IoT devices.

The 3rd Generation iPad Pro and Apple Watch series were early users of the eSim and lots of other brands now.

The provisioning and usage of an eSim can be done at the network operator’s center.

It can also be done remotely since it does not require the physical removal of sim cards.

Users of the eSim can use the settings of the eSim on their devices to change network providers unlike the physical sims.

To aid your decision when purchasing a phone/device, keep in mind that an eSim is a non-physical sim.

which means it does not come as a plastic card (credit-card-like) as the previous sim cards.

It cannot be broken nor held with your hands especially if you like to physically see your sim card.

The standard reference of an eSim is ETSI TS 102 671 V9.0.0.

three sim cards in colors red, green and orange

Do Sim cards expire?

Yes, sim cards expire based on the non-usage dates for expiry set by your network provider or Telecommunication regulator in your country.

Most operators allow for a 90-day non-usage period before the churning process starts for the sim to be terminated.

A non-usage usually refers to a non-revenue-generating activity on the sim.

In other words, a user must either make a call, send an SMS, or use the internet to initiate a revenue-generating activity on their sim cards.

Merely receiving a call or SMS does not count as a revenue-generating activity.

A user must initiate outbound activity for the network to recognize usage which can help extend the sim validity.

The life-span of a sim card also depends on how well it is handled.

Can a Sim card get damaged?

Yes, sim cards can get damaged depending on how it is handled.

Frequent removal or open exposure can erode the chip components.

Scratches from unfriendly elements can also cause damage.

Sim cards can get broken or totally stop working for technical reasons.

An easy solution to this is to get a sim replacement from your network operator if your sim card stops working.


What is a Sim card replacement or Sim swap?

A sim card replacement simply means to change or renew a sim due to damage or when misplaced.

Sim cards can be replaced by your network provider when damaged, stolen, or missing.

A list of requirements is usually requested by the network provider (via a call center or walk-in service center).

Some of the requirements may include proof of ownership, a form of identity, and so on.

The essence of a sim replacement is to seamlessly get you back onto the network as soon as possible.

Restore subscribed services on the new card while retaining your mobile number.

The replacement process is immediate or within 24 hours depending on how fast the network activates the new sim card.


What are the benefits and Who should own a sim card?

Anyone and everyone can own a sim card once they are of legal age and if mentally capable to do so.

Children who are not of age have access to communication by proxy of their parents or guardians until they get to a legal age.

Anyone who wants to enjoy the benefits of personal or business communication as it is key to our existence in today’s world.

The sim card connects us via SMS, voice, data, and other value-added services for us and businesses to function and thrive.

Every should indeed own one to stay connected to the world.

All types of businesses whether small, medium, or large in some way communicate with their clients using the sim card.

4G and 5G innovations have made communication even faster and better with businesses at the fingertips of our customers.

Anyone with a sim card and a smartphone can create a business on the spot, that in itself is transformational compared to the past.

The sim card may be small, but it is one of the tools that enable technology to reach billions of people all at once.

Social media Apps such as YouTube, Instagram, Facebook, Quora, Twitter, and many other platforms can be accessed via the connectivity the sim card provides.

Hands, phone and social media icons

Some businesses are run entirely in the online space, generating millions of profits in revenue money.

Video content creators, course creators, influencers, marketing campaigns, personal brands, e-commerce, schools, news, and more are in our spaces daily because of internet penetration through sim cards.

Access to information is now at our fingertips provided you have a sim especially one with access to the internet.

The importance of owning a sim is many through the capabilities it affords us.

Everyone should have a right to one, if not for anything for keeping us virtually connected to our family and friends. 

Communication is indeed a superpower, so equip yourself with your superpower.

Let your voices, opinions, inventions, and businesses soar through the use of your sim card, the world awaits you!