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What are eSIM and iSIM? Terms and acroymns explained
Said Gharout 
SIM technology is evolving fast and gaining rapid traction in many industries. As standards and implementations develop, there are many terms we often get asked. To help navigate the #FutureofSIM, here is a glossary of acronyms with useful explainers.
eSIM: eSIM is the generic term applied to devices and eUICCs that support Remote SIM Provisioning as defined by GSMA.
Discrete eUICC: An eUICC implemented on separate standalone hardware, including its own dedicated volatile and non-volatile memory. A Discrete eUICC can be removable or non-removable.
eUICC: A UICC which enables the remote and/or local management of profiles in a secure way that meet GSMA requirements for Remote SIM Provisioning and are certified in
accordance with the GSMA compliance programme. The term originates from “embedded UICC”.
Integrated SIM: Either an integrated eUICC or an integrated UICC.
Integrated TRE: A TRE integrated inside a System-on-Chip (SoC), optionally making use of remote volatile and/or non-volatile memory.
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Integrated eUICC: An eUICC implemented on an integrated TRE.
Integrated UICC: A UICC that is implemented on an integrated TRE and that does not support Remote SIM Provisioning as defined by GSMA.
Operator: A mobile network operator or mobile virtual network operator; a company providing wireless cellular network services. An operator owns one or more international mobile
subscriber identity (IMSI) ranges.
Profile: A combination of data and applications to be provisioned on a UICC or an eUICC
for the purpose of providing connectivity to mobile networks.
SIM: A generic term for the application(s) residing on the UICC that identify a subscriber and allow them to securely access a mobile network (e.g. 4G or 5G). SIM is sometimes used interchangeably with the term UICC or SIM card.
SIM Card: A SIM that has one of the physical plug-in form factors as defined by ETSI (i.e. plug-in, micro-SIM, nano-SIM).
SoC (System-on-Chip): A System on a Chip (SoC) is an integrated circuit (also known as a ‘chip’) that integrates all or most components of a computer or other electronic system.
TRE (Tamper Resistant Element): A security module consisting of hardware and low-level software providing resistance
against software and hardware attacks, capable of securely hosting operating systems together with applications and their confidential and cryptographic data.
UICC: The platform, specified by ETSI, which can be used to run multiple security applications.
These applications include the SIM for 2G networks, USIM for 3G, 4G and 5G networks, CSIM for CDMA, and ISIM (not to be confused with integrated SIM) for IP multimedia
services. UICC is neither an abbreviation nor an acronym.
