Cellular connectivity glossary by 1oT

The cellular connectivity and IoT industry are in constant evolution. The same can be said about the many complicated terms and concepts used in the field, sometimes making it hard to keep track of all the changes.

Therefore, we have created a jargon-busting glossary to explain terms used with eSIMs, remote SIM provisioning, and the IoT industry in general.

Click on the topic of interest and you will be taken to the right section of the page:


eSIM – an eUICC chip with an activated eSIM profile on it. To communicate with the eSIM, an eSIM ecosystem has to exist that is compliant with the eSIM standard, which defines how to remotely provision carrier profiles without having to swap out the physical card or chip inside the device. eSIM and eUICC tend to be used interchangeably but eUICC is rather part of eSIM and not the same as eSIM.

Bootstrap Profile – A profile containing one or more NAA (Network Access Application) and associated NAC (Network Access Credentials) which, when installed on an eUICC (eSIM), enables access to the communication network(s). The bootstrap profile provides transport capability for eUICC management and profile management between the eUICC and an SM–SR (Subscription Manager Secure Routing).

Connectivity Parameters – A set of data (for example, SMSC address) required by the eUICC to open a communication channel (for example, SMS, HTTPS) on a dedicated network.

Disabled Profile – The state of a profile where all files and applications are not selectable over the eUICC (eSIM) – terminal interface.

Enabled Profile – The state of a profile when its files and/or applications are selectable over the eUICC (eSIM) – terminal interface.

eUICC Certificate – A certificate issued by the EUM (eUICC manufacturer) for a specific eUICC (eSIM). This certificate can be verified using the EUM Certificate.

EID (eUICC Identification) – eUICC identifier used in the context of remote provisioning and management of eUICC.

EIS (eUICC Information Set) – eUICC information set that provides information about the state of the eUICC.

EUM (eUICC Manufacturer) – Supplier of eUICC and resident software (firmware and operating system).

EUM Certificate – A certificate issued to GSMA accredited EUM (eUICC Manufacturer), which can be used to verify eUICC Certificates. This certificate can be verified using the Root Certificate (a public key certificate identifying a root certificate authority).

Fall–back Mechanism – A function supported by an eSIM (eUICC) when an enabled profile fails to access a network. When this happens, eSIM automatically enables the fall–back profile to give the device access to the network.

Fall–back Profile – An attribute of a profile that identifies another profile enabled by the fall–back mechanism. There can only be one fall-back profile set on eUICC at a time. The profile with fall–back attribute set can't be deleted.

Operational Profile – A profile containing one or more NAAs (Network Access Applications), associated NACs (Network Access Credentials), network operator's applications, and 3rd party applications.

Profile – A combination of a file's structure, data, and applications present on an eUICC. When enabled, a profile allows access to specific mobile network infrastructure.

Profile Component – An element of a profile that may be one of the following:

  • An element of the file system like an MF, EF, or DF
  • An application, including NAA (Network Access Application) and Security Domain
  • POL1 (Policy Rule 1)
  • MNO–SD (Mobile Network Operator Security Domain)
  • Connectivity parameters

SM-DP (Subscription Manager Data Preparation) – This process prepares profiles and manages the secure download and installation of these profiles onto eUICC (eSIM).

SM-SR (Subscription Manager Secure Routing) – A process that securely performs functions of platform management commands regulates the transport of profile management commands.

Cellular Networks

APN (Access Point Name) – A gateway between a mobile network and the Internet.

CDR (Call Detail Record) – A file containing information about recent system usage. Some examples include identities of sources (points of origin), identities of destinations (endpoints), duration of each call or data session, amount billed for each call or data session, the total data usage in the billing period, and the running total charged during the billing period. The format of the CDR varies among different providers or software programs.

HLR (Home Location Register) – A database from a mobile network, where all mobile subscribers' information is stored. An HLR contains information about a subscriber's identity, telephone number, associated services, and general information about a subscriber's location.

ICCID (Integrated Circuit Card ID) number – A unique number assigned to a SIM card.

IMSI (International Mobile Subscriber Identity) – A unique number, usually consisting of fifteen digits. The number is associated with a carrier profile to identify a cellular network subscriber.

MCC (Mobile Country Code) – An MCC is used in combination with an MNC (Mobile Network Code; a combination known as an "MCC/MNC tuple") to uniquely identify a mobile network operator (carrier) using the available mobile networks.

MNC (Mobile Network Code) – A unique two-or three-digit number used to identify a home mobile network.

MNO-SD (Mobile Network Operator Security Domain) – The security domain part of the Profile. It's owned by the MNO, providing the Secured Channel to the MNO's OTA (over-the-air) Platform. It is used to manage the content of a Profile once the Profile is enabled.

MSISDNs (Mobile Station – ISDN) – A telephone number assigned to a mobile user. This telephone number makes it possible for any subscriber of the plain old telephone network to call a mobile station.

PLMN (Public Land Mobile Network) – Any wireless communications system used by terrestrial subscribers in vehicles or on foot. The system can stand alone but is often interconnected with a fixed system, such as the PSTN (Public Switched Telephone Network). The most common example of a PLMN end user is a person with a cell phone.

Roaming – Using cellular service outside of the home network coverage area. A user will be allowed to use a roaming partner's network.

Roaming Steering – Steering of roaming, or "preferred roaming," is a process where a mobile operator decides which partner their subscribers will use while roaming.

SMSC (Short Message Service Center) – A network element in the mobile connectivity network. Its purpose is to store, forward, convert and deliver SMS (Short Message Service) messages.

SMPP (Short Message Peer-to-Peer) - a protocol for enabling SMS sending and receiving.

Subscriber – An entity (associated with one or more users) that is engaged in a subscription with a telecommunication service provider. A subscriber can subscribe and unsubscribe to services, register a user or a list of users authorized to use those services, and set the limits relative to the use that associated users make on those services.

Subscription – A commercial relationship between the subscriber and the telecommunication service provider.

USSD (Unstructured Supplementary Service Data) – A GSM (Global System for Mobile) communication technology that is used to send text between a mobile phone and an application program in the network. Applications may include prepaid roaming or mobile chatting.

Radio Access Technologies (RAT)

2G – The second generation of GSM (Global System for Mobile) cellular technology. 2G improved the network performance by adding the cellular radio spectrum, which would help solve the coverage issues and drops in signal due to urban obstacles. Implementing 2G was the turning point in moving from analog transmission methods to digital by adding digital encryption and paving the way for cellular data usage. Nowadays, 2G is considered a legacy network and is being shut down worldwide.

To read more about the shutdown of 2G and 3G networks, visit our blog.

3G – The third generation of GSM (Global System for Mobile) cellular technology. It offers substantially improved data transfer rates over its predecessor, 2G. Later releases of 3.5G and 3.75G provided mobile broadband access of Mbit/s. That introduced wireless voice telephony internet access through mobile appliances and video calls to the industry. Like 2G, 3G is considered a legacy network and is being shut down worldwide.

To read more about the shutdown of 2G and 3G networks, visit our blog.

4G – The fourth generation of GSM (Global System for Mobile) cellular technology. It's currently considered the best cellular network around the world. The users get speeds up to 100 Mbit/s and introduced video streaming to the cellular connectivity field. 4G is also referred to as LTE.

To find out what cellular network is the best option for your IoT project, visit our blog.

5G - The fifth generation of GSM (Global System for Mobile) cellular technology. It introduces an amazing peak download speed at 20 Gbit/s, up to 1 million devices connected per one square kilometre, and covers connections and speeds when driving up to 500 km/h. While the technology is being implemented in more and more areas around the world, it's important to know that it's still relatively new and has a lot to improve in the upcoming years.

To read more about 5G technology and how it works with IoT, visit our blog.

LoRa (Long Range) – The LoRa Alliance is an open, non–profit organization dedicated to promoting interoperability and standardization of LPWAN (low–power wide area network) technologies to drive implementation of IoT (Internet of Things).

LoRaWAN (Long Range Wide Area Network) – A LPWAN (low-power wide-area network) technology that uses a license-free frequency spectrum.

LPWAN (Low–Power Wide Area Network) – A wireless wide area network technology that interconnects low–bandwidth, battery-powered devices with low bit rates over long ranges. The most well-known LPWAN technologies include LTE-M (Long Term Evolution for Machines) and NB-IoT (Narrowband Internet of Things).

Read more about LPWAN and its use cases in our blog.

LTE (Long Term Evolution) – A type of 3G cellular network that meets 4G network’s speed requirements, but lacks the core network features of it (for example, LTE doesn’t meet the criteria of a Wireless 4G service). The terms 4G and 4G LTE are used interchangeably, but it’s important to keep in mind that they’re not the same.

LTE-M (Long Term Evolution for Machines) – A LPWAN (low-power wide-area network) technology in licensed frequency, designed for IoT (Internet of Things) usage. It's often compared to another LPWAN technology NB-IoT (Narrowband Internet of Things), but the two have relatively different use cases.

Read more about LTE-M, NB-IoT, and which one to choose for your IoT project here in our blog.

NB–IoT (Narrowband Internet of Things) – LPWAN (Low Power Wide Area Network) technology in licensed frequency. Designed for ultra-low bandwidth IoT devices, the lowest power consumption of cellular connectivity solutions.

To read more about NB-IoT and its use cases, read our blog post on comparing NB-IoT and LTE-M.

SIMs and SIM Management

2FF/3FF/4FF SIM Form Factors – 2FF (Mini SIM), 3FF (Micro SIM) and 4FF (Nano SIM) are physical SIM form factors currently in widespread use. These SIMs are widely accessible, easy to operate with, and supported by hardware components.

To read more about SIM form factors and see which one would work best for your use case, visit our blog. 

API (Application Programming Interface) – A set of functions and procedures that allow the creation of applications. These applications have access to the features or data of an operating system, application, or other services.

Embedded SIM (MFF2) – Embedded SIM is another way to refer to an MFF2 SIM form factor, a SIM that's soldered straight into the device. Despite many articles referring to embedded SIM as eSIM, it's not correct.

iSIM (Integrated SIM) – Miniaturized SIM card integrated with the device’s processor core, using the encryption of SoC (System on a Chip), on a cellular module. With iSIM, physical chip SIMs in the form of 4FF, 3FF, 2FF, MFF2, are not needed anymore.

To read more about iSIM, visit our blog.

UICC (Universal Integrated Circuit Card) – Generally referred to as SIM card, a UICC is a smart card used in mobile terminals in GSM (Global System for Mobile) and UMTS (Universal Mobile Telecommunications System) networks.

SIM (Subscriber Identity Module) - An integrated circuit card that stores the network authentication parameters.

SIM Management Platform - A platform built to provision (e)SIMs. It has a set of functions related to changing SIM statuses, usage reports, and the ability to enable/disable and manage carrier profiles (on eSIM).


2.4 GHz – A short-range wireless band commonly used in wireless technologies, such as Wi-Fi, Bluetooth, and ZigBee.

3GPP (Third Generation Partnership Project) – A project that develops and maintains technical specifications for mobile telecommunications.

IoT (Internet of Things) – Physical objects (or groups of objects) that have been embedded with sensors, processing ability, software, and other technologies that collect and exchange data with other devices and systems over the Internet or other communication networks.

M2M (Machine to Machine) – The term refers to direct communication between devices using any communications channel, including wired and wireless. It can include industrial instrumentation, enabling a sensor or meter to send the information it records to application software.

MNO (Mobile Network Operator) – Wireless communications services provider that owns or controls all the elements necessary to sell and deliver services to an end-user, like Radio Access Network infrastructure. MNO examples include AT&T, Telia, Orange, etc.

MVNO (Mobile Virtual Network Operator) – Wireless communications services provider that doesn't own the infrastructure themselves but rents it from an MNO. Even though MVNO uses MNO's infrastructure, they may use their services (e.g. customer and billing support systems).’

OEM (Original Equipment Manufacturer) – A manufacturer that produces goods for other companies to sell under their name.

Short-range IoT (Short-range Internet of Things) – A segment that primarily consists of devices connected by unlicensed radio technologies within a range of up to 100 meters, such as Wi-Fi, Bluetooth, and Zigbee.

Wide-area IoT (Wide-area Internet of Things) - A segment made up of devices using cellular connections or unlicensed low-power technologies like Sigfox and LoRa (Long Range Alliance).