SIM: Subscriber Identity Module

Introduction

Nowadays Nowadays, SIM cards are a vital part of our day to day activities. It allows 7 billion devices to be connected to mobile networks around the world. “As per International Card Manufacturer Association (ICMA), there were 5.4 billion SIM cards manufactured every year which leads to USD 6.5 Billion revenue for card manufacturers globally”. The increase in demand for IoT and upcoming 5G technology is expected to boost the demand for SIM.

The introduction of embedded SIM (eSIM) and remote SIM provisioning (RSP) from the GSMA may disrupt the traditional SIM ecosystem and value added services of network operators.

Since they are always used on GSM phones for connectivity purposes. For CDMA phones they are only needed for LTE purposes. SIM cards are also used in satellite phones, cameras, computers and smart watches.

What is a SIM?

The "Subscriber Identity Module" also known as “SIM”, is a programmable smart card installed in a mobile device that gives access to a network. It is a smart card that contains programming and subscriber information. It is an integrated service that is used to securely store “International Mobile Subscriber Information” (IMSI) number and its related key. “IMSI” is used to identify a subscriber to a digital mobile network and it also provides the details of services which subscriber has opted for a particular mobile operated network. A SIM card is a removable plastic card with embedded memory and processor chip which is used to store and process subscriber information. Technically, a physical SIM card is called a “Universal Integrated Service Card” (UICC). This card is made with the PVC with an embedded integrated circuit from semiconductor.

History and Structure

The SIM need was initially proposed by “European Telecommunication Standards Institute” in the specification. This gives the blueprint of the physical and logical structure of SIM. When the Universal Mobile Telecommunication System (UMTS) was introduced, “3GPP” developed the application of “SIM” and “USIM”. Further to other developments, First SIM was developed by “Giesecke & Devrient” in Munich in 1991. This company also sold the first 300 SIM cards to Finnish wireless network operator “Radiolinja”.

SIM is a piece of hardware with embedded integrated circuits which allows mobile operators to connect with mobile devices. Each SIM is registered with Unique Identification Number, with other details such as −

• Personal Identification Number (PIN) - for ordinary use

• Personal Unblocking Key (PUN) - for unlocking purpose

Format of SIM Cards

For a period of time SIM has been made smaller in size, however functionality is not related to size. It is a matter of convenience in handling and also devices in which SIM is inserted is getting smaller day by day such as IoT and mobile devices.

SIM Card Format	Introduce	Standard Reference	Physical Appearance
Full Size	1991	ISO/IEC 7810:2003, ID-1	It was about the size of a Debit Card.
Mini Size	1996	ISO/IEC 7810:2003, ID-000	Removed from 11F sim card
Micro Size	2003	ETSI TS 102 221 V9.0.0,Mini-UICC	Cut out in the form of 3FF from 1FF and 2FF
Nano Size	2012	ETSI TS 102 221 V11.0.0	Further cut down from 3FF
Embedded SIM	2016	ETSI TS 102.671 V9.0.0 JEDEC Design Guide 4.8, SON-8 GSMA SGP.22 V1.0	Installation through M2M application, no physical form.

Use of SIM

Every cellular phone that exists today uses a SIM card. Without it, we wouldn’t be able to use our mobile phone for making phone calls, surfing the internet (unless connected to WIFI). Following are the prime uses of SIM cards −

• SIM cards provide control to network operators over subscribers such as services, subscription, security, data protection, etc.

• It helps in transferring information on mobile devices to the network operator through their network

• It represent the identity of network user on the network

• It helps in getting devices stay connected to the network such as IoT, Sensors, Smart Cars, GPS devices

• It help in getting all time connect to internet and work as a critical security feature in out day to day life

Conclusion

In conclusion, SIM cards as we know by now are also called, Subscriber Identity Module. As the name suggests it represents network users identity who wants to use a network which is operated by operators. It is a critical semiconductor device without which we cannot make connections to the listed network. Each SIM card represents a particular network operator, however as we roam/ travel across different network coverage areas, we get allowed to connect to other networks, which is also called “Roaming”. SIM cards were first introduced in “Finland''. With all these benefits of SIM cards, they are also prone to security loop holes. Due to which individuals are targeted by hackers, who have indirect access to sensitive data.

FAQs

Q1. Which part of the SIM is important?

Ans. The most important part of the SIM is small integrated chip which is read by the mobile in which they are inserted.

Q2. What does a SIM card contain?

Ans. It contains user information, location, mobile information, subscription plan and network operators details.

Q3. Why do we cut one corner of the SIM?

Ans. We often noticed that SIM cards are cutted from the corner. It is done in order to avoid misalignment of the SIM against the card reader placed in the mobile phone.