The Evolution of SIM Cards: From Mini to eSIMs

1. Introduction

A SIM card is a type of smart card that is used in mobile phones and in certain other devices that connect to mobile networks. It allows a user to “roam” between different devices and different networks, as long as the devices and networks are compatible with the type of card provided. The term “SIM” is the abbreviation for “Subscriber Identification Module”. Each card is uniquely identified by its Integrated Circuit Card Identifier (ICCID) and its International Mobile Subscriber Identity (IMSI) number. When the card is inserted into a device and the device is turned on, the card uses its IMSI number to check the identity of the user and of the mobile equipment. It then uses the wireless network to log on and the user can access the network services. However, with the continued reduction in size of mobile phones and other mobile devices, there has been a drive to reduce the amount of internal space that is needed to accommodate a physical SIM card slot. This drive has led to the development of smaller SIM cards, and ultimately to elimination of the need for a physical SIM card altogether. These developments have led to the development of embedded SIM cards, commonly referred to as “eSIMs”. An eSIM is a type of smart card that is built into mobile phones and other mobile devices. It contains all of the information that is needed in order for a mobile device to use a mobile network. This means that there is no need for a physical SIM card to be provided. The information stored on an eSIM can be re-written or deleted, meaning that the card is not permanently tied to a single network. This allows for greater flexibility as to the range of networks that could be accessed. Also, as the card is built into the device, there is no need to insert a physical SIM card into the device and no risk of the card and its contacts becoming damaged through use.

1.1. Definition and Purpose of SIM Cards

Sim card is the abbreviation of Subscriber Identity Module. This is a type of smart card that is used in mobile phones and other portable devices in order to identify the user of the device. The main purpose of the SIM card is to connect to a mobile network. When the user inserts a SIM card into the mobile phone, the phone identifies that SIM card and establishes a connection to the mobile network. In the same way, when a person makes a call to that mobile phone number, the mobile network uses the information stored on the SIM card in order to find that mobile phone and establish a call to it. In other words, SIM card acts as an “identity” for that mobile phone in the mobile network. Also, the mobile network stores some information on the SIM card in the form of international mobile subscriber identity (IMSI) or equivalent, which is unique for each SIM card in the whole world. This helps the mobile network to identify a particular SIM card when it is connected to the network and carry out the necessary information retrievals. Also, the SIM card is used to store some user information, such as the mobile phone address book and text messages, so that the information is portable. When a user changes the mobile phone or transfers these data to another person, he/she just needs to move the SIM card to the new mobile phone. Modern SIM cards normally store the contacts in the form of list of contacts, the user can select to save a new contact in the SIM card or in the mobile phone memory. This is very useful, because user can just move the SIM card to another phone and the contacts will be there as well.

1.2. Importance of SIM Cards in Mobile Communication

Sim cards play a vital role in providing security and authentication to subscribers when it comes to mobile communications. The majority of mobile network operators use sim cards as a way of uniquely identifying the line and service subscribed to by the user. Besides serving as an integrated circuit that securely stores the International Mobile Subscriber Identity (IMSI) and the related key used to identify and authenticate subscribers on mobile telephony devices, sim cards provide users with a mobile phone number and a storage location where Short Message Service (SMS) texts and recently dialed numbers are stored. This is particularly important for ensuring the privacy and security of users’ identity and information. A sim card works by storing the IMSI, which is unique to every subscriber, in a database known as the Home Location Register of the specific mobile network operator. It also stores a key known as the Ki. The Ki is a secret key used to encrypt signaling between the mobile phone and the mobile network and to authenticate the user. This means that, instead of the mobile phone transmitting the plaintext IMSI over the mobile network whenever a call is being made or received, the sim card can cause the mobile phone to transmit a unique character string that is made by applying the algorithms and the secret key to the IMSI. As the sim card technology continues to grow from one generation to another, advanced applications including the Authenticated Key Exchange (AKE) protocol has been developed to provide forward and backward secrecy for sim card security. This means that mobile communication security through sim cards has been greatly enhanced to a level that in case a private key stored in the sim card is compromised at any time in the future, there is a way of preventing past and future communications from being decrypted. An attacker who might gain knowledge of the secret key of the sim card, or has the ability to eavesdrop and intercept communications between the mobile phone and the base stations, is prevented from using the compromised key to decrypt past communications or eavesdrop future communications. As a result, mobile communication using sim cards remains to be a reliable and efficient way in protecting against unauthorized monitoring and interception of communications as well as ensuring the security of each individual subscriber’s identity and information.

1.3. Overview of SIM Card Evolution

At their inception, SIM cards utilized the standard credit card dimensions. These were standardized in full-size (85.60 mm × 53.98 mm × 0.76 mm), mini (25 mm x 15 mm x 0.76 mm), and micro (15 mm x 12 mm x 0.76 mm) sizes. As of now, the most commonly used size for SIM cards is the micro SIM card, although eSIM offerings are gaining popularity. There are currently three sizes in usage today: full-size, mini, and micro. Full-size SIM cards are not commonly used in modern handsets. However, mini and micro SIM cards are much more widely utilized. SIM cards have evolved in fashion and size since the first ever SIM card was produced in the full-size dimension. Nowadays, contemporary cards are almost exclusively in mini size.

2. Mini SIM Cards

Moving to chapter 2, in the late 1990s, there was the next significant reduction in size to the 25mm x 15mm credit card format, which is the size we will all be familiar with as a “normal” SIM today. This project was an initiative of the mobile phone German D2 network, supported by the large SIM card manufacturer Giesecke & Devrient, and later on, the digital mobile phone leader Siemens. This initiative became known as the “TS 11”, and it quickly gained widespread acceptance, resulting in the “TS 11” format being adopted by the GSM association. This format reduced the size of the protective plastic around the SIM from 5mm to 2.8mm in both width dimensions, and to only 0.9mm thickness. This project allowed for a lot of feedback and development suggestions to be brought together with industry experts and working groups. As a result of this collaboration, a large number of involved parties could focus their supply chain on mini SIM cards and devices that are compatible with them, benefiting from economic savings of scale. It was the experience of successfully managing a transition between two card sizes and form factors, coupled with the earlier success of the “Karte 1” and “TS 11” projects, that led to the most aggressive form factor exercise of the SIM card roadmap so far – the “SIM 21” project, which sought to define a build specification for the UICCC, or “embedded” SIM form factor in 2016.

2.1. Introduction to Mini SIM Cards

Sim cards were first invented in 1991 by Munich smart card maker Giesecke and Devrient. Initially, they were the size of a credit card. However, with technology evolving and mobile phones getting smaller, a smaller version of the sim card was needed. This gave birth to the mini Subscriber Identity Module card, or mini sim card, in 1996. The introduction of the mini sim card was to enable its use in ultra-compact mobile phone handsets that had been designed for the micro browser mobile phone standard. The technical standard for a mini sim card is the full-size 1FF (1st form factor) integrated circuit chip. The actual mini sim is 25mm by 15mm in size with a thickness of 0.76mm. The mini sim card, also known as the second form factor (2FF) was popular with most mobile phone handsets for a long time with the exception of feature phones but has a number of pins and advantages over its predecessor, the full-size sim card. These advantages include less overall plastic in the construction, meaning that tumbling and manufacturing is simpler. Also, there is a possibility of more memory in a mini sim card due to surface area being saved in cutting the plastic package size down. However, there are also some disadvantages and limitations of using mini sim cards which include the fact that they do not operate in new class of mobile phone handsets (Class H) which promises much greater power saving enhancements and network interactivity, the sim card module is more complex and has extra conductive pins that the full-size sim, the potential of connecting to background wireless networks is present, such as hot spots, but the extra power consumption required for a mini sim card to operate may have a significant effect on battery life. Also, failure to operate at 3V and 1.8V could be an issue. The smaller sim cards, the micro and nano sim cards, are cut from a plastic frame that is a mini sim card as the gold contact area is the actual raised chip. However, mini sim cards are backwards compatible, meaning they can function and are accepted in mobile phone handsets which use full-size sim cards. Also, a mini sim card can currently be used with a mobile phone capable of operating with a micro or nano sim card with a sim card adaptor. Ideal mini sim card sizes can be found by following the link and it is important to remember that mini sim cards hold a considerable amount of personal and sensitive data. It is imperative that when fully removed from a mobile phone, the sim card is safely stored away and, when it is no longer required, the sim card is physically destroyed as it is possible for persons to recover information after deletion.

2.2. Advantages and Limitations of Mini SIM Cards

On the other hand, as many new devices are manufactured with either the micro or nano SIM card slot, users with a mini SIM card may find it more challenging when looking to purchase their next device. Users with a mini SIM card have reported that there are fewer devices to choose from and users may find that their choice of device is limited to older models.

Finally, the mini SIM card size measured at 25mm × 15mm, which was a significant downsizing by comparison to the full-sized SIM card. This reduction in size resulted in freeing up more internal space for potential hardware and allowed for a more consolidated motherboard within a device. Also, the minimization of physical space taken up by the SIM card allowed for mobile device manufacturers to include a larger screen area which was a design feature that has been relatively popular with devices in recent years. Despite the increasingly common adoption of the micro and nano SIM cards, the mini SIM card is still recognized and widely used across smart technologies today from mobile phones to GPS and 4G and 3G enabled tablets. Additionally, the contacts area on a mini SIM card remained the same, so there was no shrinkage of the user’s data space on the card itself which seems to be the way forward with the micro and nano SIM cards nowadays.

Secondly, the full-sized SIM card, which its dimensions measured at 85.60mm × 53.98mm, was a large card by comparison that took up far more internal space within the external hardware of a mobile phone. This extra space often had to be taken from space that could be used for incorporating other hardware components and in more recent years, affecting the hardware of the mobile device itself. However, as the demand for more data storage within SIM cards was recognized, the advantages of reducing the size of the card and freeing up internal hardware space became important. This, in turn, led to the development of the mini SIM card.

Firstly, if a user needs to change their device for any reason, all of their user data is safely stored on the SIM card and can be transferred with ease. This method also makes it very easy for a user to change their mobile device and is generally more efficient. This was not a possibility that was initially possible with the standard-sized SIM cards due to the difficulty and time consumption of the amount of user data that had to be manually transferred from one device to another.

2.3. Mini SIM Card Compatibility with Devices

Mini SIM cards are distributed as 3 in 1 to accommodate the valid competent devices that the SIM card may be utilized in ranging from the Standard SIM, Micro SIM, to the Mini SIM as portrayed by Kevin K on October 8, 2016. In accordance to Shina, a legitimate contributor to a forum board elaborates that the Mini SIM card provides for the 3rd most ability in terms of device compatibility with the decision to shrink the SIM card made as a result of the advancement in technology which has led to the construction of slimmer and more portable devices. Manufacturers have come up with smaller variants of SIM cards such as the Nano SIM card to improve the infringing sizes that come with newer devices and so as to make room for other applications like micro SD cards. A Mini SIM card or a 2FF measures 25mm by 15mm and offers the 2nd most competence as compared to the Standard and Micro SIM cards in terms of device adaptability. Any modern day advanced phone that can’t accommodate the common Standard SIM card sizes will certainly recognize Mini SIM cards. The SIM cards have the same purpose of storing data for purposes of verification and connection accounting in a mobile network. The shape and dimensions of Mini SIM cards have been properly defined by the European Telecommunications Standards Institute and this has been widely accepted by mobile phone manufacturers because these are the recognized standards to comply with. With the advancement in technology, newer phones are adapting the use of the Nano SIM card which is 40% smaller than the Micro SIM card but this is made possible through the use of an adapter to conveniently fit into devices with a larger SIM card slot.

3. Micro SIM Cards

In 2003, a new type of SIM card, the micro SIM card, was introduced to consumers for the first time. As the name suggests, the micro SIM card is much smaller than its predecessor, the standard SIM card, measuring only 12mm by 15mm – a reduction in surface area of around 52%. This was an important step as mobile phone handsets began to get smaller in size and manufacturers were demanding even more real estate for additional components. The decreased overall size and increased locality around the dedicated SIM card slot meant that mobile phone manufacturers could accommodate many of the features required in a modern mobile phone handset. Initially, the success of the micro SIM card was driven by the introduction of the Apple iPad in March 2010 – until this point, the device had only used full-sized SIM cards to provide cellular connection. When Apple announced that a micro SIM card was required and that the device would be available flagship in the UK utilizing the high-speed HSPA+ data connection, mobile network operators had to rapidly start to produce micro SIM cards for the first time in order to allow proper utilization of the new device. A micro SIM card is, of course, backwardly compatible with a standard SIM card and so the large surface area contains only one SIM card chip. By fracture lines are written into the plastic and gold contact pads are regularly placed over the joining lines in order to retain the essential compatibility. The removal of excess plastic around the connectors provides the space-saving that is so crucial to the successful development of the micro SIM card format. Gradually, over a period of time, manufacturers of the standard and larger mini SIM cards have moved to adapt production processes to allow the micro format to become the predominant choice across the industry. The micro SIM card remains widely used in most of the newer devices on the market today, including the iPhone 4 and 4s varieties as well as the new and exciting iPad tablets. In 2012, a push towards the nano SIM card format led primarily by Apple in its new iPhone devices caused some industry speculation that the use of the micro format would begin to decline but this was not the case based on the continued wide range of products on the market that still require micro SIM cards.

3.1. Introduction to Micro SIM Cards

Micro SIM cards were invented to help deal with the issue of lack of space. In reality, SIM cards which were in operation were substantially bigger than the modern day micro SIM cards. Due to the fact that phones and technology, on the whole, were improving and getting smaller – something had to be done in order to address the issue of taking up too much space. When the invention and creativity of the micro SIM card was signed off, the next step was to make it accessible for the wider public. Few phones had the technology to facilitate micro SIM cards. However, in the modern era, the majority of phone providers and contracts provide micro SIM cards. Adaptors have been developed for people that own phones with different SIM card slots. By using the adaptors, a micro SIM can be placed inside and made equivalent to a standard SIM card. In doing so, data can be transferred from phones of different SIM types and a single number can be used across various SIM cards.

3.2. Advantages and Limitations of Micro SIM Cards

One of the most significant advantages of a micro SIM card is that it can allow for both increased storage space and a near field communications chip to be installed on the card with relative ease. This ultimately means that modern devices with these capabilities, such as Google’s Nexus range of smartphones designed to exploit the potential of the Android operating system, have the option to manufacture a micro SIM card. In addition, a further advantage of the design is that when a micro SIM card is used in a device, such as a smartphone or a tablet, that uses a standard SIM card size, then it is simply a case of inserting the micro SIM card into the adaptor provided to make the card compatible with the device. However, the chief limitation of the micro SIM card technology as it stands is the simple fact that it is so new; meaning that there are still a significant number of devices on the market, such as feature phones, that utilise the standard size SIM card. Unfortunately, as micro SIM cards require a slightly different voltage to standard size cards, it is impossible to use the former in the latter type of device without resorting to a potentially damaging bodge such as shaving down the plastic of the micro SIM card or winding copper wire around the contacts of the card so as to widen the card to the size of a standard SIM card – both of which are relatively risky procedures. In addition, while full size SIM cards (i.e. ‘smart’ cards) have a well-defined method of soldering on the individual contacts to a printed circuit board within a device, the mini SIM cards have little in the way of established methodologies for fitting inside a device and ensuring it remains secure; this can be seen as an example of where standardisation and technology in general has lagged behind the trend in card technology. Also, when a network operator or service provider issues a micro SIM card to a customer, then upon swap of the user data from an old SIM card to a new micro SIM card, it is the standard practice that the old card is deactivated. This means that, in the interim in which a micro SIM card is in the mail or the user has not yet swapped the data from the old SIM card to the new micro SIM card, then there will be no service. This can be an inconvenience both for day-to-day users and for certain machine-to-machine applications that rely on constant service.

3.3. Micro SIM Card Compatibility with Devices

Micro-SIM cards were designed to be backwards-compatible, meaning that a user can adopt micro-SIM as their SIM card on newer devices integrated with micro-SIM slots. However, the devices which use only mini-SIM, getting those devices using micro-SIM is quite problematic. But still there is a solution to use the micro-SIM developed for such devices. That is by using the plastic, which can be placed surrounding the micro-SIM chip in order to be the same size as mini-SIM. This kind of SIM card is known as mini-UICC. The contact area of micro-SIM is 12.3mm x 8.8mm on the other hand mini-SIM’s contact area is 15mm x 12mm. The new micro-SIM connector created by the micro-SIM card development had shown an impressive performance, with reliability per 10,000 mating cycles which is 5 times superior than the mini-SIM connector. For the forward-compatible, micro-SIM cards are able to be inserted into mini-SIM slots with the use of adapter. This shows that micro-SIM and mini-SIM are compatible for each other in terms of the physical systems. However, it doesn’t explain how the actual hardware and software work together with the carrier subscriber networks and their data. In the next blog, I will talk about studying existing solutions and attempting to answer how they might allow mini-SIM users to change over to micro-SIM as a standard card.

4. Nano SIM Cards

The next evolution in SIM card miniaturization is nano-SIM. It is approximately 40% smaller than micro-SIM and has the same thickness. Nano-SIM with its 12.3×8.8×0.67mm physical dimensions is the smallest of them all. The actual card functionality and interface for each type is the same. Therefore, nano-SIM is backward compatible with mini-SIM or micro-SIM. But mini-SIM or micro-SIM is not forward compatible with nano-SIM. This means that if a mobile phone uses a nano-SIM, then the same nano-SIM can be used in all other phones from different phone manufacturers. But if a mobile phone uses a mini-SIM or micro-SIM, then only the same card type or a compatible larger card can be used. The circuit in nano-SIM is the same as in others and the only change is a reduction in plastic around the circuit. This small reduction in plastic around the circuit makes the nano-SIM delicate. Though there is a reduction in size and plastic around the circuit, there is no change in the contact area. Also, the thickness of nano-SIM is similar to that of micro-SIM, which is 0.67mm. This makes the design of mobile phone simpler. When the number of mobile phone users is increasing, it is impossible to obtain a mini-SIM or a micro-SIM immediately. Therefore, these days all new mobile phone networks and network operators are provisioned to offer nano-SIMs. Also, mini-SIMs are not available for some years. Therefore, some network operators provide micro-SIM with a blanking part. This means that a mini-SIM and micro-SIM combined card is supplied and users can cut the suitable SIM type. However, users are not advised to cut bigger SIMs into smaller ones using the card as a guide because cutting too close to the contacts could damage the SIM.

4.1. Introduction to Nano SIM Cards

Launched in 2012, the nano SIM card marks the fourth variation in SIM card size. Nano SIM card measures a mere 12.3mm by 8.8mm by 0.67mm and is 40% smaller than the micro SIM card and 12% less in thickness as compared to the micro SIM card. Despite its minute size, it is very effective and convenient. Nano SIM card finds its place in the modern smartphones while the preceding models (the mini SIM card and micro SIM card) are on the brink of elimination. Unlike its predecessors, the cards used in certain iPads such as iPad Air and iPad Mini exclusively require nano SIM cards. However, users still have the possibility of converting their bigger or smaller SIM cards to nano SIM card size. Modern iPhones such as iPhone 5, iPhone 5s, iPhone 5c, iPhone 6 (standard and plus), iPhone 6s and iPhone SE use nano SIM cards. Upon release, the Apple professionals claimed that the reduction in SIM card size has provided more space for other important modules and components in the modern-day smartphones. A striking hallmark of the nano SIM card is its design. Its edges are beveled at an angle of 45 degrees. This standardized design is aimed at further minimizing the chances of error during installation of the card in the phone. The central part of the nano SIM card that houses the primary data is absolutely indented, probably to facilitate a secure and firm hold on the card by the SIM card tray within the phone. This could be useful in protecting the card against accidental disengagement from the SIM tray. Ergonomically, the nano SIM card seems to be perfect. It demonstrates a thoughtful design and shows an evident display of technical progress in the area of mobile telecommunications. Despite the complexity in cutting and shaping the original size SIM card to the nano SIM card, the whole process is quite straightforward, especially when one uses the correct tools like the cutters with the right adapters. This is credited to the precise and accurate dimensions of the nano SIM card.

4.2. Advantages and Limitations of Nano SIM Cards

The greatest advantage of the nano SIM card is that it helps manufacturers create much slimmer devices, because previously they needed the extra space for the regular SIM card. Apple is one of the pioneers in adopting the nano SIM card with the launch of iPhone 5. Advantages include reduced risk of card damage, faster data speed and lower power consumption. As the nano SIM card is much smaller than the standard or micro SIM card, it greatly minimizes the risk of the card being damaged when you insert or remove it in the SIM card tray or any devices. This is because standard and micro SIM cards are quite flexible compared to the nano SIM cards. For instance, iPhones including iPhone 5, iPhone 5S, iPhone 6, iPhone 6 Plus, iPhone 6S, iPhone 7 and iPhone SE all use nano SIM card. As to Samsung Galaxy smartphones, starting from Galaxy S6 and Galaxy S6 Edge, they use nano SIM card. The very first limitation of nano SIM card is that the card itself is much smaller than the other versions which means it can be easily lost if not taken care of properly. Secondly, a damaged nano SIM card might affect the antenna or affect the connectivity of the electronic devices so it is important to take note of the condition of the nano SIM card and replace one when needed. Thirdly, to use a nano SIM, your wireless carrier may provide a nano SIM card or a micro SIM with a nano SIM card adaptor. Using an incorrectly sized SIM card may jam the card and damage the card slot. This is definitely inconvenient in particular when you are not at the place to get it fixed immediately. Because the card is much smaller and thinner than the standard and micro SIM cards, it may be harder to handle or see compared to the other SIM cards. This is especially when you need to change or replace the SIM card since most of the adapters used to convert the nano SIM card size back to the standard or micro SIM card size are not firmly built and the nano SIM card can be stuck in the adapter easily as a result. On the other hand, the software operators will execute their own tests and checks on a certain electronic communications and this has been recognized. However, the software may crash or show some unknown behaviors after some period. The performance and efficiency of the nano SIM card in mobile communication for a certain limited group of mobile devices have been examined with the tests on the radiation and battery consumption and some particular results are acquired. Also the compatibility between the SIM card and the devices has been discovered as described in EN 103 200 for the application toolkit features to be used for the internet communication. Through a number of test measurements on antenna, specific absorption and total isotropy power, test assessment on radiation has been carried out and a particular compliance with the limit has also been found. On the other aspect, the efficiency of the battery charging time and the power life with the application in the mobile communication with the various types of nano SIM card have been examined. Based on the feedback and voltage measurement at some designated gauge hours, the ability of the SIM card in the provision of secured and fast communication with the mobile devices have been evaluated and discovered.

4.3. Nano SIM Card Compatibility with Devices

The scenario is similar with its new Nano SIM card technology where the card is being used. The truth is that many users face compatibility problems when they are trying to use a Nano SIM card in a Micro SIM or standard SIM card slot. The scenario is like there will be a larger slot that will be too large to fit the Nano SIM. In this case, there will be compatibility problems. However, if the users are looking to fit a Nano SIM card into a standard SIM or Micro SIM slot, it is usually easier to make a Nano SIM fit properly. This is because the Nano SIM can easily be converted into the larger Micro or standard SIM size through a process known as cutting the card. The process involves physically cutting the Nano SIM into either Micro or standard SIM size which will make it easily fit. The Nano SIM card is used to connect mobile devices to the mobile networks, so unless in a few isolated situations, it is unlikely that compatibility problems with a particular device will occur for as long as the device uses the standard Nano SIM card. The card is readily available now because it has been used for a while and new smartphones and most of the network providers use Nano SIM cards. This type of technology is not going anywhere soon, thus it’s worth investing in a device that uses a Nano SIM card. The use of Nano SIM card technology is frequently advancing. With the increasing complexity of smartphone technology, it is now possible to own a SIM-enabled smartwatch or a smart device for enhanced mobile experiences. It’s no longer just smartphones that adopt this technology. All these smart devices that are using Nano SIM card technology have led to better and more improved functionality of the devices.

5. eSIMs

The Apple Watch (from Series 3 onwards) and most major smartwatch manufacturers offer eSIM compatible devices; in the case of the Apple Watch, this feature is not exclusive to the high-end models and works even on the cheaper Series 3 edition. It’s clear that eSIM technology is poised to drive progress in designing and connecting IoT and wearable devices, and the first signs of this impact are beginning to emerge in the consumer electronics market.

Thanks to their ability to change their connections ‘over the air’ and host multiple profiles, it is possible for an eSIM to allow a smartwatch, for example, to freely move between different networks to maintain the strongest available signal, or for a remote sensor or smart device to be ‘reprogrammed’ to connect to a new network without having to undergo any manual alteration.

In addition, the technology works with a wide range of devices. Because physical SIM cards need a tray or slot to hold them, smaller and non-traditional device designs have not been able to use the technology, hence why even the most modern smartwatches, fitness trackers and cameras all feature a SIM tray somewhere on the device’s body. However, as eSIMs don’t require a slot, they are a great fit for the emerging world of wearable and ‘internet of things’ (IoT) technology.

By contrast, a physical SIM card is stuck with the one network to which it is assigned, unless it is physically removed and replaced with a different card, and a device’s SIM slot cannot support multiple cards. The ability for users to add and remove mobile network profiles on demand makes eSIMs extremely flexible and represents a major step forward compared to the old SIM swapping.

A traditional SIM card, as previously mentioned, is a small chip that holds user data in the solid state, and is provisioned by the SIM card issuer, being physically inserted into a compatible device. An eSIM, however, is rewritable and can be updated ‘over the air’, meaning that it can change the network to which it connects, the things for which it can be used, and the personalisation data (like the user’s phone number and PIN). This capability to host multiple mobile network operator profiles is a key advantage of eSIM technology – one card can work with a variety of different network providers, is not tied to a device, and doesn’t have to be removed or inserted into a different device to be compatible.

eSIMs, now finally beginning to displace their bulkier, plastic-encased forebears, really do mark a significant point in the evolution of SIM cards. The eSIM (the ‘e’ stands for ’embedded’) is a digital SIM card which exists as a chip, soldered onto the device’s motherboard. Its intention is to support a more seamless interaction between the user’s personal device and their mobile network, being reprogrammable and having the capacity to host multiple user profiles.

5.1. Introduction to eSIMs

In recent times, the wireless industry has seen a large-scale migration from using traditional SIM cards worldwide to the embedded SIMs. What exactly is an embedded SIM? It is a small chip that is embedded inside your phone that does the same job as a SIM card. Also known as eSIM, this smart piece of technology is rewritable so you can change your network operator whenever you like, and it is compatible with all devices. A lot of modern cell phones and smart devices, such as smartwatches, are coming with eSIM technology; this includes all the latest iPhones and Samsung phones. This automatic adoption of eSIM by big network providers and mobile network operators is a sign of the direction in which technology is going, offering a smaller, virtualized, and more convenient solution to mobile subscriber identity and authentication. The increased development of eSIM production is helping to drive down the build costs of these devices, ultimately reducing the bulky plastic waste associated with the traditional SIM cards. However, unlike the traditional SIM card that can be kept by the user, the eSIM is already being mass-produced and pre-installed into the devices by the manufacturers.

5.2. Advantages and Limitations of eSIMs

To continue, eSIMs are becoming more sought after due to their benefits. eSIMs provide lower costs for subscription and are also less likely to be damaged. Firstly, as eSIMs can be remotely activated or changed without the need for a physical replacement, this would reduce the costs required for replacing the physical SIM. Furthermore, an eSIM can be reprogrammed at any time, allowing the owner to switch between mobile carriers as many times as they would prefer to. This means that the user can conveniently change their network subscription for a holiday abroad and then switch back to their usual network afterwards, for example. In contrast, the user would not be able to change their network subscription as frequently as they would like to with a physical SIM card. From a commercial perspective, this could increase competition in the mobile phone industry because it would be easier for consumers to change their network subscription. On the one hand, it may encourage mobile network providers to provide a higher quality service in order to keep existing consumers. On the other hand, it may encourage these mobile network providers to compete on price in order to attract new consumers. However, the full potential of eSIMs cannot be realized at the moment because most mobile networks do not provide support for eSIMs. In addition, not all mobile phones are equipped with eSIM compatibility. For instance, as of December 2019, this is the case for the Apple iPhone XR. A limitation can arise from the fact that if the device linked with the eSIM is lost or damaged, the information stored in the eSIM may be irretrievable. However, this would not be the case for a physical SIM because it can be removed and transferred to another device. Also, the use of QR codes or a download link to add a profile to an eSIM may be a concern for those who are particularly cautious when it comes to cyber security and privacy.

5.3. eSIM Compatibility with Devices

After understanding what eSIMs are, it is necessary to evaluate how versatile they are. Technically, eSIMs can work for any device from smartphone to printers and routers because devices are being created to support new technology. Firstly, it is interesting to examine how eSIM works on smartphones. In comparison to the most recent phones in the market from Apple and Samsung that have physical SIM card slots, only the Google Pixel 2 is the one that uses eSIM and this is like a test run. According to Google, the reason why they made this move from physical SIM card to eSIM was because of the port and speaker design. The current SIM card slot of the phone may allow water to get inside and subsequently, cause damage to the port or the speakers. By removing the SIM card slot at the expense of integrating eSIM, the Google Pixel 2 can be water resistance so that the port and the front facing stereo speakers will be better protected against splashes. Also, manufacturers may want to avoid paying patent fees to use SIM card slot designs. There have also been many tests to show that eSIMs are compatible with more than just smartphones. Owing to the increasing demand for machine-to-machine communications, eSIM technology is fast becoming a standard feature in new IoT devices like Fitbit and Galaxy Watch. The main advantage of an eSIM is that it can be remotely added to a global mobile network and it can hold multiple network profiles so that a device can switch from one network to another. On top of that, the eSIM is soldered onto the circuitry instead of being a physical and interchangeable card. This reduces the space used by the SIM and frees up design space so that manufacturers can put additional features into their products such as better antennas which improves the wireless efficiency. A greater efficiency in wireless technology will not only boost the growing IoT sector for better connectivity but also reduce cost of provisioning individual SIM cards and the associated shipping and packaging for consumers, resulting in a positive impact in our environment.

6. Comparison of SIM Card Types

Each of the three major subscription types offers different benefits and limitations. First off, it is worth mentioning that using a traditional SIM often involves a great deal of inconvenience during the subscription process. During registration, you might be asked to provide certain identification details such as your name, your physical address and sometimes even a proof of address, your date of birth, or perhaps a copy of your ID or passport. To facilitate this, many international carriers have adopted a method of scanning this information and storing it in the physical SIM cards they provide. This then permits direct access to these details so long as the SIM remains within the device, allowing immediate and seamless identification. The downside to this is that every time a new device is used or a new subscription is opened, all of this information has to be reapplied. This makes this method logistically challenging and time-consuming for anyone who requires frequent and flexible access to mobile connectivity. Provisioning an eSIM, on the other hand, does not require the user to navigate such a tortuous process and does not require the storage of personal identifiers within the eSIM. In line with EU regulations on digital identity, mobile users have the right to store and manage their electronic identifiers without undue influence from other parties. Therefore, the first time a mobile subscription is activated, users can scan in and verify their identification details from a secure digital source, such as a passport. From that point onwards, the subscription details can be directly and instantaneously updated by the user via the mobile network. Compounded by the fact that secure digital methods of identification are starting to become internationally recognised, it is likely that the advantages of the eSIM process far outweigh the transition away from traditional SIMs.

6.1. Size and Form Factor Comparison

The most important characteristic of a SIM card is its size and form factor. At first, SIM cards were as big as a credit card, but now the majority of the SIM cards are small. The following figure shows the sizes of mandatory and optional SIM cards. The figure shows that the physical dimensions of SIM cards have decreased over the years with the SIM card size getting fractionally smaller each time. The first SIM card ever was the size of a credit card (85.60 mm × 53.98 mm × 0.76 mm) and it is referred to as an ID-1 type. It had a lot of unnecessary surrounding plastic too, at least in the technology point of view. It was a Standard SIM. Then it has been shrunk to Mini SIM (25.00 mm × 15.00 mm × 0.76 mm) and this was the SIM card, which first widely came into the market. It is also called a 2FF SIM because it was the second form factor of SIM cards. Later on, Mini SIM transformed to Micro SIM which is a 3FF SIM. According to the standard of SIM cards, the length and width of Mini to Micro has to be reduced but the thickness has to remain the same. So, a Micro SIM is identical in thickness to a Mini SIM. Then to Nano SIM – the latest version of SIM cards – and it is a 4FF SIM. This change requires further reduction of length and width and also thin down to 0.67 mm. It is expected to have additional reduction for the remaining size in the future, for another number of functionalities and applications used. Comparing the sizes of different SIM cards, Nano SIM is about 12.3% from Standard SIM in length, 18.1% in width and 52.6% smaller in size area. I have seen that some Nano SIMs have a detachable Micro SIM adapter.

6.2. Storage Capacity and Performance Comparison

On the other hand, the latest type of SIM cards, which is the embedded SIM or e-SIM, and traditional SIM card has the significant difference between the sizes. The e-SIM cards have an extremely light weight and just come in one size. This makes it far smaller than the traditional SIM card, and even the smallest traditional SIM card available, which is the nano SIM. With this tiny size, the potential of the e-SIM being damaged due to the card being bent or scratched is significantly lower. Taking into account about the storage capacity, since the older version of SIM card, the storage has increased continuously. The traditional SIM cards have a little space to store the 20 text messages and only one contact while the latest and previous version of SIM card have the ability to save up few hundred contact numbers. On the other hand, the storage of the e-SIM still yet to disclose by the mobile manufacturer. However, the e-SIM definitely will be able to store more than what the current SIM cards can do today. This is due to the subscription information is already being installed in the e-SIM, thus the remaining space can be used for additional function such as contact, message or even as a small capacity of memory. The performance of traditional SIM cards is quite slow at the moment. When something is saved into the SIM card or deleted from it, there is always a wait and this can be very annoying. This is due to the traditional SIM card normally has the storage which is 3v which mean that SIM card cannot process or read data very fast. However, the new version of SIM card is available with the little progress. The performance over the operation whenever related to the saving or deletion process has improved; however it is still depending on different mobile phones. On the other hand, the e-SIM is known to provide the advantage in terms of its performance which is the faster in term of data transmission rate. This is due to the e-SIM use the latest technology which is called as embedded field programmable gate array (e-FPGA) that is currently used in Telecommunication and Electronics industry. The e-FPGA structure can be reconfigured million and million times in the field and it can perform the multiple advanced digital processing functions at the same time. Last but not least, it is quite tedious and time consuming whenever need to change the mobile network by using the traditional SIM card. First the user need to go to the service provider and make the request to change the network before the service provider will gave a new SIM card with new number while the remaining active period and some credit will be transferred to the new account. After that, the new card number need to be registered in a manual manner for the contact information transfer. However, by using the e-SIM, it is so simple and can be done with just a few clicks. The user can simply selected and sign in the different mobile network through the mobile screen without physically change the SIM card. And also, the e-SIM card allow for the even easier sign up process for the new mobile service; especially it is beneficial for the customer when want to apply the mobile service online. The service can be activated instant once the customer confirm the service request and there is no need for the waiting for the card delivery, time for activation by the postal or even the need to queue up in any mobile store.

6.3. Flexibility and Convenience Comparison

References: – GenApple G, “How to remove your SIM card from your iPhone”, available: [Link] – Google, “The latest: Google hails eSIM technology as it discusses Pixel 2”, available: [Link] – Lui, L, “eSIM: What is it and why it’s important in the next generation of smartphones”, available: [Link] – Chris Woodford, “SIMs and smartphones”, available: [Link]

Students are replacing physical SIM cards with eSIM profiles: The most significant advantage of an eSIM is that it’s programmable, which means that it can be updated over time to add new mobile operators or new subscription profiles. Also, Google has commented that eSIMs will make it easier for consumers to switch between services because the SIM will become an even more fundamental part of the mobile phone. Also, it is worth pointing out that eSIMs are very small; the chip itself only measures at 6mm in length, 5mm in width and 0.09mm in depth. This means more space for chassis and internal components of the phone. Another important advantage of eSIM technology is that it will remove the hassle of removing and inserting physical SIM cards when switching to a new phone from another model. Any customer can switch between mobile services using the phone settings, which is a lot easier and less stressful. Also, technical support agents would not have to worry about damaging SIM cards or handsets anymore. This will make switching between services easier and can promote competition between mobile network operators. As a result, consumers will have a greater choice of services and they may benefit from improving contracts and services. Furthermore, the flexibility of eSIMs will lay the groundwork for more technologies to improve phones in the near future. For example, because the SIM is programmable via software, it is likely that mobile phones featuring eSIM technology could incorporate ‘over the air’ updates for the SIM. This could mean better network coverage or new high-speed mobile services can be made available to consumers as soon as network operators make them available. Also, the SIM could be easily updated to fix mobile connectivity issues. However, there may be a chance of eSIMs being susceptible to hacking or malicious viruses as the technology develops. The eSIM market must be carefully monitored and important security standards must be imposed to ensure secure use of the technology.

First, the physical SIM cards only work with phones that have the appropriate slot. There are 3 different SIM card sizes and if a customer changes their phone then it’s likely that they’ll also have to replace their SIM card. This means when customers decide to switch to a new phone from another model or change their mind, they would have to remove and insert the physical SIM card. Normally, a customer would have to push a pin into the smaller hole next to the SIM tray slot to remove the slot. After that, the agent would have to slot the SIM card out of the tray and put it back into the new phone, slotting it all the way in until a click is heard. This task can be fiddly and due to the frail nature of the SIM card with its exposed gold connectors, there’s a rather high chance of the SIM card being damaged. Also, the SIM tray has to be positioned carefully to avoid any damage to the connectors on the phone.

7. Future Trends in SIM Card Technology

While the traditional SIM card form factors are still in use today, the industry has gradually moved towards the eSIM standard. The eSIM brings a few advantages to the table. For instance, eSIMs are pre-installed in a device and so can be activated or reprogrammed remotely. This makes them extremely convenient for connected devices, which might need to switch between different networks without any user input. Such “over-the-air” provisioning can save valuable time and costs, particularly in remote applications. As the adoption of eSIMs continues to grow, we can expect more devices and applications to take advantage of this technology. In terms of SIM card technology as a whole, it is likely that future designs will have a heavy focus on allowing smaller and smaller form factors. The move from regular to micro to nano and now eSIM represents a clear trend. Integrating SIM cards within IoT devices in both industrial and consumer markets is likely to become increasingly important if the potential of the IoT is to be realized. There is great potential for manufacturers to develop solutions that exploit the vast range of different sensors and communications systems opening up with the IoT revolution, and indeed some companies have already made significant headway in this area. The move to remote provisioning of SIM cards seen with the eSIM standard will continue to streamline production and reduce the logistical load of deploying large IoT systems, making it ever easier to realize IoT projects of all shapes and sizes.

7.1. Potential Innovations in SIM Card Design

As miniaturisation in SIM card design continues to the level that only the chip would remain, there should be enhanced security features embedded on it. For example, incorporating biometric technology such as fingerprint recognition or being able to recognise the eye iris within the SIM cards can be a potential breakthrough in the realm of SIM card technology. The potential for integrating biometric features in SIM cards is quite high as efforts to have a more secure way of confirming the identity of smart card users have already been made, mainly for enhancing security in the banking sector. Also, it may be possible that SIM card manufacturers would venture into the use of advanced materials to improve the physical integrity of the card. For instance, the potential for making use of nano-structured polymers in the design of future SIM cards could lead to greater resistance of the card to mechanical stress. Moreover, these advanced materials could pave the way for the seamless integration of antennas within the SIM card. This would be a potential development, especially with the increasing interest in the use of SIM cards that incorporate components of the Internet of Things. By having the SIM card with its own antenna, it could exclusively communicate with end devices more effectively, broadening its areas of applications beyond mobile telecommunication. Also, continued miniaturisation in SIM card design would capacitate the creation of a standardized SIM-embedded system that allows end users to not only use that technology for wireless communication but also benefit from a plug-and-play style of set-up for any devices.

7.2. Integration of SIM Cards in IoT Devices

The next topic outlined in the evolution of SIM cards concerns the innovative ways that IoT device developers are integrating SIM cards in their devices. Historically, to use IoT devices which require cellular connectivity, the owner has to sign up with an MNO to get service on their SIM, as described earlier. This brings a lot of overhead with cellular IoT, where every SIM has to have a distinct address and security credentials to the network. To help mitigate the increasing costs of managing mobile subscriptions (like ordering sims, negotiating contracts with MNOs, and fixing issues in case of rewrite limits), new methods of integrating cell modules are being introduced. One of the popular methods from the late 2010s to today is allowing the sale of “Cloud-Connected Cellular Modems”. These are cell modules that do not require any form of SIM card or registration to an MNO – instead, the modem connects to a cloud service on the Internet using shared security credentials. This concept isn’t new – devices like Amazon Dash Buttons have used WiFi to connect to the Internet and order products for years. By connecting a cellular modem to a cloud service, products can be developed with the ability to connect directly to an IoT cloud platform out the box, with zero configuration needed on the user end. This is often referred to as “zero touch” deployment. Instead of having a physical SIM card and a subscription to a cellular network, users have only to register their product to their account on the cloud service. These kinds of products are more commonly found in the consumer market, where ease of adoption and minimal steps to get products working are desired. However, as cellular connectivity becomes more and more vital, new advances are pushing for methods that don’t require any manual steps for connecting products to the Internet. By using the shared security and trust framework provided by the cloud service, we can develop products that allow near instant deployment and product testing for the commercial market. As well as reducing the need for physical SIM management, the use of a cloud service provides the product with a scalable connection to the wider Internet. New trends are being established for SIM card technology – in fact, under the 3GPP Release 14 for LTE – Advanced Pro, standards are currently being developed to introduce three different “levels” of support for SIM-less operation, from partial reliance on the cloud service all the way to total disconnection from the cloud. By providing the cellular modem with a way to authenticate and communicate over an encrypted link to connect to the cloud and Internet, this allows a universal method for producing IoT products with cellular capability that can stand the tests of the consumer and commercial markets. These technological advances are combining to accelerate the adoption and use of cellular IoT products in all sectors of industry; so next time you find yourself developing that revolutionary new product, keep an eye on the transforming world of SIM card technology!

7.3. Impact of eSIMs on Mobile Network Operators

The lack of eSIM lock-in contracts and the elimination of physical SIM card distributors, such as network operators, will make it possible for MNOs to expand internationally with no requirement for funded distribution partners. With no requirement to pay a worker to manually prepare a SIM card and the required physical materials necessary, the average cost to provision a new MNO customer will dramatically fall. The low barriers to entry when connecting a new customer and the ability to connect with any network at will, without having to discuss a contract with a network operator, will lead to global expansion economically achievable, enhancing the ability for global IoT solutions serviced by various mobile network operators, where currently this can only be serviced by a single or very few networks. As a result of increased global expansion and the ability to attract a global customer base, those MNOs with successful IoT solutions will grow at an exponential rate – due to the ability to provision new customers cheaply and the potential market size now including the whole world, instead of just the customers in the MNO’s local market program. All of these examples lead to the conclusion that eSIMs will revolutionize the way MNOs consider their target demographics and markets – it will be difficult for MNOs to argue for a primary focus on local customers when the cost to both market and provide a product to global customers is becoming so decreased. On a final note, the potential for ‘out of market’ customers to have the ability to connect to a device on any network, regardless of that network’s restrictions, either through the use of consumer accessible eSIM profiles or some later advanced technical workarounds known only at this early stage in the eSIM revolution, challenges the current systems regarding MNO account security and control. Nevertheless, the potential for a global customer base that is no longer restricted by the customer’s location ensures that eSIM technology will be driving disruptive change in the current and established mobile network market – revolutionizing MNO strategies and opening up the potential for global expansion for any competitive MNO on the market today.

8. Conclusion

All types of SIM card don’t offer significant advantages, but eUICCs do offer considerable new possibilities that will form the basis of new business models in the coming years. eSIMs (or to use the correct definition of the physical hardware, eUICCs) have overcome the issues associated with previous attempts at programmable SIM solutions. Arriving on the consumer market after the complete failure of the only previous attempt at this technology; the programmable SIM (also known as the SoftSIM or SIM on Chip), the eUICC is a technological marvel in comparison. Offering the same convenience of a simple, digital connection change without the need to wait for delivery of a new physical SIM, eUICCs allow the level of connectivity enjoyed by many smartphone users to be expanded on a scale not previously possible. Telecoms companies may use data records stored on a SIM to help price contracts, justify payments, or coordinate actions performed by a network to add extra protection for account security. Research is focused on removing residual barriers to the complete obsolescence of the traditional, physical SIM card. There is a sizable and well-justified recycling and second-hand market for SIMs, but the environmental costs of production and disposal of millions of plastic and metal SIMs each year are considerable. The explored types of SIM cards are directly relevant in considering how different types of mobile networks can interact with the devices that access them on a physical level. As the security and compatibility of SIM technology develops, it enables all the more potential for different mobile network types to be used in novel applications such as those in the Commercial Internet of Things and autonomous vehicle technology.