eSIM은 기존 탈착식 SIM 카드를 대체하는 단말 내장형 보안칩 형태의 SIM으로, SIM 카드 데이터를 서버에서 eSIM으로 다운로드하는 기술입니다. 기존 단말 사용자는 대리점을 방문해 통신서비스에 가입하고 SIM 카드를 발급받지만, eSIM 단말 사용자는 크게 향상된 사용자 경험을 누릴 수 있습니다. 단말을 통해 통신사 및 요금제를 선택하고, 온라인상에서 SIM 카드 데이터를 다운로드하여 쉽고 편리한 통신 서비스 가입과 통신사 변경이 가능합니다.

또한 eSIM 단말은 단말 제조사에게는 단말 소형화 및 방수/방진 설계, 통신사에게는 오프라인 대리점 운영 비용 및 SIM 카드 물류비용 절감 등의 이점을 제공합니다. 이러한 장점에 힘입어 eSIM 단말은 점유율을 높여가고 있으며 eSIM 표준 규격을 담당하는 GSMA는 eSIM 탑재 단말의 수가 2030년까지 67억 대로 증가하여, 전체 스마트폰 연결의 76%를 차지할 것으로 예상하고 있습니다.

GSMA는 기존 SIM 카드를 대체하고, 다양한 단말 제조사, 통신사, SIM 카드 제조사 간의 상호연동성을 제공하기 위해 SIM 정보를 다운로드하고 관리할 수 있는 기본 기능을 포함한 eSIM V1과 V2 표준 규격을 2016년에 발표했습니다. 이후 SIM 카드 대비 eSIM 사용의 불편을 해소하고 그 이상으로 사용자 경험을 향상시키기 위해, 기기 변경 및 듀얼심 지원 등을 포함하는 eSIM V3 표준 규격을 2022년 10월 발표하여 표준을 발전시키고 있습니다. 본 블로그에서는 이러한 eSIM 기술 및 표준화 진행 현황에 대해 알아봅니다.

The traditional removable SIM (Subscriber Identity Module) card (hereafter 'SIM card') has played a fundamental role to securely store subscription data and credentials which are used to authenticate a device accessing the mobile network. SIM card is issued by a mobile carrier and an end user needs to insert the SIM card into a device to access the mobile carrier’s network. The embedded SIM, or eSIM, is a programmable SIM card which is soldered inside a device. To use an eSIM to access a mobile carrier's network, a "Profile" needs to be downloaded from a Profile Server (so-called SM-DP+) to the eSIM inside the device as shown in Figure 1 (right). Profile is a software package containing subscription data and credentials that were originally defined to be stored inside a classical SIM card, and a Profile installed on an eSIM plays the same role as a classical SIM card.

Furthermore, a single eSIM is capable of holding multiple Profiles (up to its memory capacity) and the end user can manage (e.g., enable, disable, or delete) the installed Profiles via the device UI. Once a Profile is enabled, the eSIM, with the enabled Profile, operates as a SIM card.

With these fully digitalized characteristics, the eSIM provides greatly enhanced user experience by allowing users to subscribe and activate mobile services in a fully online manner without having to visit an operator shop to sign up a subscription and get a SIM card.

Figure 1. Removable SIM card vs. eSIM

GSMA (GSM Association) was founded in mid 1990s to encourage the use of GSM technology, and became a global organization which has more than 1,100+ member companies and provides industry-wide standards including eSIM.

In 2016, GSMA published eSIM V1 standard (hereafter 'eSIM V1') for the use of eSIM in consumer devices, especially for companion devices such as smart watches. eSIM V1 only supports the installation of only a single Profile on an eSIM, considering this specific device category. With eSIM V1-equipped device, to switch from one to another Profile, the existing Profile on the eSIM has to be deleted before installing a new one. Later, eSIM V2 standard (hereafter 'eSIM V2') was released to support the use of eSIM in smartphones as well as in companion devices. In consideration of smartphone use cases, it allows for a user to install more than one Profile on an eSIM and manage them via device UI. Most of the eSIM devices in the market today are based on eSIM V2. The procedure of remotely provisioning a Profile into an eSIM is called as "Remote SIM Provisioning" (RSP) in the GSMA eSIM specifications, and Figure 2 illustrates the overall RSP architecture.

Figure 2. Overall RSP architecture [1]

RSP architecture consists of the following four main components:

• SM-DP+ (Subscription Manager - Data Preparation+): a Profile server owned and controlled by each operator
• SM-DS (Subscription Manager - Discovery Server): a centralized discovery server to help a device find the SM-DP+ server holding a Profile for it
• LPA (Local Profile Assistant): a software component on the device to manage Profiles on the eSIM
• eUICC (embedded Universal Integrated Circuit Card): the standard terminology of eSIM, in particular meaning the "physical eSIM chipset"

Recently, GSMA published eSIM V3 (hereafter 'eSIM V3') last October [2], which provides new features improving user experiences with eSIM. More specifically, eSIM V3 introduces 'eSIM Device Change' and 'Multiple Enabled Profiles' as its key features.



eSIM Device Change

Figure 3. eSIM V3 Device Change

With a classical SIM card, when a user needs to change from the old device to a new one with the same subscription, she/he can simply do it by moving the SIM card from the old device to the new device, without any assistance from the carrier. With an eSIM V2 device, however, a user needs to contact the carrier's online/offline customer care center to request for the device change, and then the carrier will provide a new Profile to be downloaded to the new device and deactivate the existing Profile on the old device. This is probably the only worse user experience of eSIM compared to the classical SIM card as of eSIM V2.

In order to improve the user experience of the eSIM device change, GSMA has standardized 'Device Change' feature in eSIM V3, which allows a device manufacturer to provide a standardized means for a user to change her/his eSIM devices using a function provided by the device, without having to contact the carrier's customer care center as in eSIM V2. In eSIM V3 device change, on behalf of the user, the device conducts necessary communication and integration with the carrier's relevant servers in a standardized way.

Multiple Enabled Profiles (MEP)

Figure 4. Dual-SIM support (eSIM V2 vs. eSIM V3 with MEP)

eSIM V2 supports installation of multiple Profiles in an eSIM as explained above. However, it has a restriction that only one Profile can be enabled at a given time, and hence, it cannot enable multiple Profiles simultaneously. As a consequence, most eSIM V2 devices in the market provide Dual-SIM functionality with a combination of eSIM and physical SIM card as illustrated in Figure 4 (left).

On the other hand, eSIM V3 devices will be able to provide Dual-SIM functionality with eSIM only as shown in Figure 3 (right), by taking advantage of the MEP (Multiple Enabled Profiles) feature defined in eSIM V3 that allows a device to enable more than one Profile at a time. The MEP feature, in this aspect, is expected to accelerate the deployment of eSIM-only devices in the market.

GSMA has collaborated with ETSI (European Telecommunications Standards Institute) to standardize MEP feature as the interface between a modem and an eSIM also needs to be updated, under the scope of ETSI standards. ETSI has defined a new multiplexing mechanism for that interface to support GSMA eSIM MEP feature [3].

In February 2016, Samsung launched Gear S2 classic 3G in the market as the world first device equipped with an eSIM compliant to GSMA eSIM V1 [4]. Starting with this, Samsung continues to roll out various eSIM-enabled wearable devices and smartphones in European and North American markets.

In August 2022, Samsung released Galaxy Z Fold4 and Flip4 as its first eSIM-enabled smartphones in Korea. Korean carriers also started their support for eSIM smartphone activation in September 2022, ushering in a new mobile era with eSIM in Korea.

Samsung Research has been actively involved and leading GSMA eSIM standardization from eSIM V1 to V3, and also contributing for successful commercialization of Samsung eSIM products. Samsung Research will continue developing innovative eSIM technologies to provide enhanced user experiences and values with future eSIM devices.