The IoT RSP – An Improvement on the eSIM M2M RSP

In July 2023, the GSM Association (GSMA) published the technical specifications for eSIM IoT (i.e., embedded subscriber identity module for Internet of Things). Prior to the introduction and publication of the eSIM IoT remote SIM provisioning (RSP) standard, enterprises and organizations that wanted to transition to eSIM for their machine-to-machine (M2M) connectivity had to rely on the M2M RSP specifications.

This was the primary reason the embedded-format M2M SIM card (and eSIM M2M) did not really take off, especially when compared to the consumer eSIM market. The consumer eSIM segment grew significantly as original equipment manufacturers (OEMs) scrambled to join the eSIM race and drove the rise of eSIM-capable consumer devices.

The new eSIM IoT RSP standard and specifications can effectively bridge the gap between consumer and enterprise eSIM adoption. In fact, Juniper Research predicts that the number of IoT eSIM and iSIM (integrated SIM) connections globally will grow by almost 700%, from 165 million in 2024 to 1.3 billion in 2028.

Note: iSIM is like eSIM, but the subscriber identity module is integrated into the chipset instead of being on a separate chip soldered onto the circuit board.

Here are three reasons why the eSIM IoT standards and specifications are such an improvement on the earlier M2M RSP.

1. SM-DP+

SM-DP+ is short for Subscription Manager Data Preparation Plus. It is a remote server that provides both secure routing and data preparation and is a vital component of the eSIM IoT ecosystem. SM-DP+ is responsible for the following tasks, among other things:

• Generating eSIM profiles using the available information on device specifications, device capabilities, and the connectivity plan provided by the mobile network operator
• Securely transmitting eSIM profiles to authorized eSIM-enabled devices
• Managing eSIM profiles remotely, activating, deactivating, and updating profiles as needed

The consumer eSIM RSP also uses SM-DP+. The unified secure routing and data preparation platform makes eSIM and remote provisioning seamless for end-users.

How about the eSIM M2M RSP? In the M2M RSP standard, the secure routing and data preparation functions were the domain of two separate servers: SM-DP for subscription management data preparation and SM-SR for subscription management secure routing.

This caused problems. For one, it meant SM-DP and SM-SR required rigorous integration.

2. eSIM IoT Profile Manager

The eSIM IoT specifications require an eSIM IoT remote manager (eSIM). The eSIM is a program that can sit on a computer, tablet, or mobile device, interfacing between the device and the SM-DP+ server for remote SIM provisioning and management.

eIM performs the heavy lifting for eSIM IoT devices. It enables not only the push model of remote SIM provisioning, which is the hallmark of eSIM M2M but also the pull model of the consumer eSIM RSP. This makes eSIM IoT highly flexible and suitable for even the most memory-, space-, bit rate- or interface-constrained eSIM IoT devices.

This is yet another advantage eSIM IoT has over eSIM M2M. Without an eIM equivalent, the latter relies on the push model of provisioning and management to make eSIM connectivity available to constrained devices. However, this means M2M devices’ embedded universal integrated circuit card (eUICC) — the component of the eSIM that makes it capable of storing network profiles — must be configured at the time of manufacture.

This makes the whole M2M eSIM system relatively inflexible. If an organization changes its connectivity provider, the eUICC on IoT devices has to be reconfigured. That’s not a simple or inexpensive process.

In contrast, the eIM can be configured at various stages of the eSIM lifecycle. It can be set up at eUICC manufacture, at device manufacture, and even after device deployment. The eIM ensures enterprises with eIM-enabled eSIM IoT systems can easily change connectivity vendors, shift network plans, and even respond quickly to future changes in regulations and circumstances.

3. Application Layer Protocols

The eSIM IoT RSP also expands the number of application layer protocols that eSIM-capable devices can use when interfacing with a remote provisioning server.  The following are examples:

• Constrained Application Protocol (CoAP): CoAP is an efficient, lightweight communication framework suitable for slow, low-power, and low-bandwidth eSIM IoT devices. It operates over user datagram protocol (UDP), a connectionless communication protocol that enables packet transport across networks, and uses datagram transport layer security (DTLS) to secure communications.
• Hypertext Transport Protocol (HTTP): The eSIM IoT RSP also allows hypertext transport protocol (HTTP) transfers over transmission control protocol (TCP), a connection-based protocol for exchanging messages over a network, and uses transport layer security (TLS) to encrypt data for security.

The availability of different communication protocols means remote provisioning is possible for a broader range of constrained and non-constrained IoT devices. In eSIM M2M, eSIM profile activation and management were available only through short message service (SMS) and hypertext transfer protocol secure (HTTPS).

eSIM IoT RSP: Better for Enterprises and Organisations

Before the eSIM IoT standard and specifications, enterprises had to rely on eSIM M2M for business eSIM applications. For instance, a hotel that wanted to automate its solar water heater systems had to rely on restrictive, inflexible, and engineered eSIM M2M systems.

With the advent of the eSIM IoT RSP, organizations will find implementing eSIM solutions easier. The unified secure routing and data preparation server, eIM, and expanded application layer protocol options mean eSIM connectivity is available to more IoT devices and is easier to effectuate and maintain.