Currently mobile service is distributed on a plastic SIM card that must be purchased and inserted into a device. As SIM cards are becoming smaller and now require a tool to replace them in a device this is inherently more expensive, less reliable and problematic. Whereas most other ‘digital’ services can be purchased online and downloaded ( or streamed ) to a device. Examples of this are music, movies and eBooks. The connected car is being designed with inbuilt eSIM’s ( or eUICC’s ).
The GSM Association ( GSMA ) have developed a standard that has been accepted by most of their member operators around the world ( details here ). This allows the intrinsic ‘digital signature’ content of a SIM card to be downloaded ‘Over-The-Air’ ( OTA ). They initially referred to this as ‘Remote SIM Provisioning ( RSP )’ and the chips that facilitate this were known as eUICC’s ( Embedded Universal Integrated Circuit Cards ), however these chips and the whole technology are now being referred as part of the wider eSIM terminology.
There are 2 different kinds of eSIM, one that is used in Machine to Machine ( M2M ) devices like connected cars and the other that is used in Consumer devices like mobile phones.
eSIMs offer significant advantages over conventional removable plastic SIM cards. They are smaller, more robust and can be remotely programmed. Their programability means that a single skew of device can be made for several countries and removes the need for expensive field engineers to replace the SIMs in an M2M application.
In order to remotely provision an eSIM it is necessary to have some software loaded in a server which is called ‘Subscription Manager ( SM )’. The Subscription Manager for an M2M eSIM has 2 components, one is called the SM-DP ( Data Preparation ) and the other is called the SM-SR ( Secure Routing ). The SM in the consumer world has combined and enhanced both functions and is called an SM-DP+.
In the consumer world it is preferable to have a server where the end user can discover what mobile services ( profiles ) are available. This is called a Discovery Server ( SM-DS ).