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The definitive IoT glossary (2022)

Are you trying to better understand IoT? Our IoT glossary defines the most important terms you need to familiarise yourself with for IoT.
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The Internet of Things (IoT) makes our physical world digital and is already proving to be a massive boon for our society. But IoT's mish-mash of acronyms and complicated concepts can make it hard to understand the details.


This glossary is here to help you better understand IoT.



2G (Second Generation Cellular Networks)


2G is the catch-all acronym used to describe second-generation cellular networks. 2G is GSM (Global System for Mobile Communications) based and supports phone calls and SMS. 2.5G uses GPRS and supports data connections as well. 2.75G utilises EDGE (Enhanced Data Rates for GSM Evolution) for faster data connections. 2G remains very useful for IoT applications, but operators are currently phasing 2G out in multiple regions.


3G (Third Generation Cellular Networks)


3G introduced the UMTS (Universal Mobile Telecommunications System) and includes faster data connection speeds through new modulation schemes and better handover with interconnected RNCs (Radio Network Controllers). 


3.5G utilises HSDPA and HSUPA (High Downlink/Uplink Speed Packet Access), allowing even faster data speeds. 


3.75G goes further again with HSPA+ (Evolved High-Speed Packet Access +) and increases data connection speeds once more.


3GPP (Third Generation Partnership Project)


The 3rd Generation Partnership Project (3GPP) develops and maintains technical specifications for mobile telecommunications. 3GPP is an engineering organisation, and the technical specifications they develop are turned into standards by the seven standard organisations that 3GPP unites (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC).


4G (Fourth Generation Cellular Networks)


4G was introduced to deliver high uplink and downlink speeds for modern multimedia requirements (e.g. video streaming). 4G networks should provide download speeds of up to 100 Mbps.


5G (Fifth Generation Cellular Networks)


5G is the state-of-the-art for cellular communication. It's currently being rolled out worldwide (with surprising controversy in some regions) and will offer high-speed bandwidths of up to 1Gbps. Apart from being fast, the technology also provides low latency and can support massive amounts of devices in small areas (no more cellular outages at music festivals, for example).


6LoWPAN (IPv6 over Low-Power Wireless Personal Area Networks)


6LoWPAN (IPv6 over Low-Power Wireless Personal Area Networks) is a protocol where every node in a low-power wireless mesh network has its own IPv6 address. This specification enables the efficient transmission of IPv6 packets through compression and other optimization mechanisms. Onomondo currently uses IPv4.


API (Application Programming Interface)


An Application Programming Interface (API) is a software intermediary that makes it possible for two different applications to communicate.


APN (Access Point Name)


An APN is something that needs to be set when a device uses data. When an IoT device sends data, the MNO (Mobile Network Operator) uses the APN to assign the device an IP address so that it can connect to the internet.


Most connectivity providers have different APNs for different countries. Note that in some cases, devices connecting to 4G will not need to set the APN because it will get this information directly from the network.


The APN for Onomondo is always "onomondo" no matter where your device is (a big help for our customers as they never need to change it). So they can produce a device and not know in which country/region it will end up.




AWS IoT is an IoT Cloud platform owned and operated by Amazon. This platform can help developers integrate IoT devices into AWS IoT-based cloud solutions, enabling the devices to connect to cloud services that AWS provides.


Azure IoT


Azure IoT is an IoT Cloud platform owned and operated by Microsoft. This platform provides services across edge and cloud that connect, monitor and control IoT assets.


Base Station


The device transmits to a base station (aka cell tower). Base stations are the antennas you can typically see around the city on rooftops.


CAT M1 (Category M1)


Azure IoT is an IoT Cloud platform owned and operated by Amazon. This platform provides services across edge and cloud that connect, monitor and control IoT assets.


Cellular Network


A cellular network is a wireless communications network distributed over land through cells which include transceivers known as base stations. These base stations establish a connection to a device through radio signals. Each base station uses different frequencies from nearby cells, avoiding interference and increasing service quality.


CL (Coupling Loss)


Coupling Loss (CL) denotes the energy loss that occurs when energy moves from one medium to another. It's the measurement used to evaluate coverage in telecommunications. Expanding on this concept, Maximum Coupling Loss (MCL) is the maximum loss in the conducted power that a system can tolerate and remain operational (defined by a minimum acceptable received power level). A higher MCL means there is a more robust link between transmitter and receiver. 


You can read more here Maximum Coupling Loss -


Client Isolation


Client isolation prevents a device from reaching other devices on the same network, including computers and servers on wired networks.


Core Network


To keep it simple, you could say the main parts of the cellular core network are the HLR/HSS and the GGSN/PGW.


Every mobile network has a server that stores SIM information, such as location and authentication keys. The Home Location Register (HLR) or Home Subscriber Server (HSS) is the database of all the SIM cards an operator has.


The gateway GPRS support node (GGSN) and Packet data network GateWay (PGW) is where all the data a device tries to transmit goes through.


The core interfaces with other operators and the cloud, for example. You can also control what's happening in the core with APIs or apps (e.g., connectivity platforms) and proactively access information via Webhooks.


Would you like to know more about cellular IoT networks? Then you can read our post Cellular IoT Networks Explained.


eDRX (Extended Discontinuous Reception)


Extended discontinuous reception (eDRX) is a power-saving feature used in IoT devices. It reduces power consumption by extending the period where a device is not contactable. Developers can change how long a device stays in low-power sleep mode. eDRX can be used with or without PSM.


You can read more here LTE-M Deployment Guide to Basic Feature Set Requirements.


eUICC (Embedded Universal Integrated Circuit Card)


Sometimes called eSIM, eUICC stands for Embedded Universal Integrated Circuit Card and is a software profile implemented on a SIM. eUICC is purely software and only refers to the OS (operating system) on the SIM. eUICC can be used on embedded SIMs and regular SIMs, so having an embedded SIM doesn't guarantee that you have eUICC, and vice versa. 


The main advantage of eUICC is its ability to host as many carrier profiles as you want. Operator switching means you could have AT&T and Vodafone on a phone and switch between the two at will, for example. 


Operator switching is the most significant advantage eUICC has over UICC. However, Onomondo makes OTA (over the air) operator switching possible with regular UICC cards thanks to our core network setup.




A gateway is a device that sits between multiple networks or applications. It is responsible for converting data and communications from one protocol to another.




Geofencing is a location-based service in which GPS or RFID is used to create a virtual geographic boundary. This service enables businesses to accurately track and alert when devices enter boundaries, defined by triggers set up by an administrator.




Geotagging is the process of adding metadata to media based on the coordinates or location of a mobile device. This metadata can be assigned to photos, videos, websites, text messages, and QR codes.




The Global System for Mobile Communications Association (GSMA) is a global body representing mobile network operators' interests. GSMA includes over 750 operators and almost 400 companies from the broader mobile ecosystem (device makers, software companies, etc.).


Home Automation


A system that uses IoT devices to monitor and automate different functions and processes within a home environment.


IIoT (Industrial Internet of Things)


The industrial internet of things (IIoT) is a subset of IoT specific to industrial applications, such as manufacturing and robotics.


IoT (Internet of things)


The Internet of Things (IoT) is a generic term for "the network of physical objects that contain embedded technology to communicate and sense or interact with their internal states or the external environment", according to GSMA.


IoT Cloud Platform


An IoT Cloud Platform is a network that facilitates the information sent from IoT devices and applications. These platforms store data, deliver computing infrastructure and provide a database for IoT devices.


IoT Development Board


A printed circuit board with hardware designed to facilitate the experimentation and development of an IoT device.


IP (Internet Protocol)


The method or format by which information is sent from one computer to another on the internet.


IPv6 (Internet Protocol Version 6)


The next generation of IP, designed to replace IPv4, the current generation protocol. IPv6 supports 128-bit addresses on an operational network, up from 32 bit on IPv4. This new protocol can support an infinite number of addresses.


LoRaWAN (LoRa Protocol)


A wireless protocol designed specifically for both long-range and low-power communications. It is primarily used in battery-operated devices to connect them to the internet in regional, national, or global networks.


LPWAN (Low-Power Wide-Area Network)


LPWANs (Low-Power Wide-Area Networks) are low frequency and low power networks. They're designed to send small packages of data across long distances without using up too much power, which is the goal of most IoT projects. LORA, SigFox, NB-IoT and LTE-M are popular examples of LPWAN technologies.


LTE (Long Term Evolution)


Long Term Evolution, sometimes known as 3.95G, is based on GSM/EDGE and UMTS/HSPA technologies. Although it's sometimes marketed as 4G, LTE is part of 3G because it doesn't meet all of the 4G criteria. LTE+ or LTE Advanced meet 4G requirements, on the other hand.


LTE-M (Long Term Evolution for Machines)


LTE-M (aka LTE-MTC and CAT-M1) is a low-power wide-area (LPWA) technology built for the Internet of Things (IoT). It has the benefits of reusing existing LTE infrastructure, low device power consumption, high uplink/downlink speeds, high penetration (indoor coverage), and seamless handover support (mobility).


You can read more here NB-IoT vs LTE-M: A comparison of the two IoT technology standards.


M2M (Machine-to-Machine)


Machine-to-Machine (M2M) is a broader term than IoT. M2M refers to any network technology that allows devices to communicate with each other (e.g. Ethernet, Wi-Fi, cellular etc). 


IoT For All has a good article exploring the differences between IoT and M2M.


MCU (Microcontroller Unit)


A microcontroller unit (MCU) is essentially a tiny computer. The single IC (integrated circuit) chip contains a CPU (central processing unit), RAM (random-access memory), and peripheral drivers for GPIO (general purpose I/O) and communications interfaces such as UART (Universal Asynchronous Receiver/Transmitter) used to communicate with the modem.

MCUs usually focus on one or two simple tasks. The computational ability of IoT devices is usually driven by MCUs, making them vital for IoT.


Mesh Network


A group of devices acting as a single network. In cellular connectivity terms, a mesh network comprises a group of radio nodes.




Unlike traditional SIM cards, the embedded form factor (Embedded SIM aka MFF2) is built to last longer in industrial conditions, such as high vibrations and high-temperature ranges. Therefore, MFF2 chips are a suitable choice for most IoT applications.




In GSMA terminology, MIoT stands for Mobile Internet of Things and covers 3GPP standardised low power wide area (LPWA) technologies using licenced spectrum bands (LTE-M, NB-IoT and EC-GSM-IoT). Devices connected via NFC, Bluetooth or WiFI are part of IoT, but not MIoT. 


In 3GPP terminology, MIoT stands for Massive IoT and describes 5G's ability to support large amounts of devices.


MNO (Mobile Network Operator)


Mobile Network Operators (MNOs) are companies that own the RAN (Radio Access Network) infrastructure. Verizon, AT&T, Telefonica, Vodafone, China Mobile, and Telenor are examples of MNOs.


Mobile Credential


A mobile credential is a digital authorization for a device, adding additional layers of security.


MQTT (Message Queuing Telemetry Transport)


A messaging protocol designed for devices limited by low bandwidth. It operates on a publish/subscribe system, enabling bidirectional communication between devices and servers.


MVNO (Mobile Virtual Network Operator)


MNOs lease access to their infrastructure to Mobile Virtual Network Operators (MVNOs). This arrangement isn't just for some extra revenue; it's also required by law in most countries (you can read about the Danish case here Competition policy in telecommunications: The case of Denmark). However, many MVNOs are merely resellers of SIM cards who use roaming agreements and don't have any technical access to RANs.


To differentiate, sometimes you'll hear an operator call themselves a "full MVNO", which means they run the entire network technology stack. A few MVNOs, like Onomondo, rent access to the base stations themselves (this is very rare). And the way Onomondo accesses base stations is the same way an MNO attaches to their base stations (which is standardised by GSMA).


The other "full MVNOs" that we know of generally only do this with one MNO partner, e.g., Deutsche Telekom. So this integration gives them full access to data on the integration and devices on the MNO's network, but not for other RANs in the world not operated by e.g. Deutsche Telekom. Onomondo does this with over 700 local operators on the other hand.





NB-IoT (Narrowband IoT)


Narrowband IoT (NB-IoT) is a Low-Power Wide-Area (LPWAN) technology built for the Internet of Things (IoT). It includes such benefits as improved indoor coverage (high penetration), support for a massive number of low throughput devices, low device costs, low device power consumption, and optimised network architecture.


You can read more here NB-IoT vs LTE-M: A comparison of the two IoT technology standards.


Network Whitelist


Onomondo's Network Whitelist feature tells your device which networks it can connect to. For example, it will say the device can connect to Deutsche Telekom in Germany, Telenor in Denmark, and AT&T in the US, and only those operators in those places.

A Network Whitelist does not have the order of preference that a PLMN list has. Instead, your device connects to the first strong enough network. This functionality shortens registration times and avoids scenarios where e.g. devices repeatedly try to connect to weak networks before stronger options.

A forbidden network list (FPLMN), on the other hand, tells your device that it, for example, can't connect to Orange in France, but anything else it finds is fine (you can find out how to clear FPLMN lists with AT commands in our help section).


PLMN (Public Land Mobile Network)


In short, a PLMN (Public Land Mobile Network) is a mobile operator's cellular network in a specific country. Each PLMN has a unique PLMN code. This code is created by combining an MCC (Mobile Country Code) and the operators' MNC (Mobile Network Code).


When you receive a SIM from an operator it will often have a PLMN list on it. This list is a way to hardcode a prioritised list of networks you would like to use on the SIM.


Typically, the PLMN list is based on commercial agreements. So, for example, an MNO will have contracts in various countries for your SIM to connect to specific networks whenever you roam outside their network.


A negative consequence of a PLMN list is that your device could prioritise networks with weak signals over networks with strong signals.


If there is no PLMN list, 3GPP states that the radio module should attach to a strong enough network (also called -85 dBm, it's a signal strength that is strong enough to deliver a consistent, stable data connection).


You can read more about PLMN lists here Common problems with IoT SIMs: PLMN lists.


PSM (Power Saving Mode)


It's common in IoT that cellular devices infrequently send and receive data. It's possible to lower the power consumption in IoT use cases by using Power Saving Mode (PSM) when available on the RAN (Radio Access Network). PSM is a device state where the device is powered off but remains registered with the network, and so there's no need to re-attach when exiting this state. PSM can be used with or without eDRX.


You can read more about PSM here LTE-M Deployment Guide to Basic Feature Set Requirements.


QoS (Quality of Service)


The use of technologies that work to guarantee a network's ability to run high priority applications and traffic under limited network capacity. This capability enables network administrators to assign the order packets are handled, along with the bandwidth provided to that application.


Radio Access Network (RAN)


Groups of base stations are called radio access networks (RANs). As a part of the telecommunication network, the RAN sits between the device and the core network.


You could say RANs link users or devices to their operator, and the operator's core network is the gateway to external networks, such as the cloud (think Azure IoT Hub, AWS IoT Core, IBM Watson IoT and Google Cloud IoT Core), and is also how operators connect to one another.




When using your SIM outside of its home network, some of the data handling responsibility is handed over to the network you're visiting. This network is called the visited network or foreign network. In short, you're roaming when you go outside of your home network.


As a basic example, if you take a UK SIM card to the US, you can't see BBC online anymore because a local network has given you a local IP.


It's fine to roam on an iPad or a phone; you can get an SMS, make a call, and access the internet. But with IoT, some limitations can make a big difference in global deployments.


You can read more about roaming for IoT here Common problems with cellular IoT networks: Roaming.




A sensor is a device with limited resources and power designed to gather information and communicate with other nodes.


Sensor Network


A group of sensors that each monitor and record data in unique locations and forward data to a central location for storage and analysis.




Sigfox is a long-range, low-power cellular technology used for wireless communications. It's primarily used as a solution for IoT and M2M applications.




SIM stands for Subscriber Identification Module. It's primarily used to store the International Mobile Subscriber Identity (IMSI) number and related encryption keys. It's a micro-computer in itself and can run applets, for example.


There are five primary SIM types: Full-Size (FF1), Mini-SIM (FF2), Micro-SIM (FF3), Nano-SIM (FF4), and Embedded SIM (MFF2, previously referred to as VQFN-8).


The FF1 SIM card is the oldest of the five and also the biggest. Over the years, the size of SIM cards has gone down, which comes with obvious hardware benefits — such as extra space.


Each SIM size comes with one of three software options: ICC, UICC, and eUICC.


Smart Meter


A smart meter is a device designed to record data and communicate information to a consumer or service provider. These devices are used to provide regular and accurate updates over wireless networks.


TCP/IP (Internet Protocol Suite)


TCP/IP is the standard network model and communication protocol used on the internet. It consists of four layers such as listed here; application layer (HTTP, TLS, DNS), transport layer (TCP, UDP), network layer (IP), and link layer (Ethernet, Wireless LAN).

Internet Protocol Suite is responsible for packaging, addressing, and routing data sent over the internet.

If Onomondo platform users use Traffic Monitor, packets will include the information of Network Layer and above.




Telematics is the method of monitoring vehicles, equipment, and other assets. It is a segment of networking that exchanges information over long-distance transmission.


Traffic Monitor


Traffic Monitor is a tool developed by Onomondo for analyzing traffic being sent from IoT devices to the cloud. It's excellent for remotely debugging deployed devices and is also a powerful tool for developing IoT solutions.





Ubiquitous Computing


Ubiquitous computing is the potential of the total, widespread adoption of connected devices and their benefits. Also known as pervasive computing, it can be described as the saturation of devices ingrained in work, life, and logistics.


UE (User Equipment)


User Equipment (UE) encompasses various devices that connect to networks (including mobile phones, IoT devices, computers). UE is separate from infrastructure, which is the equipment UE connects to for telecommunication services and includes the access network and core network.


You can read General UMTS Architecture (3GPP TS 23.101 version 8.0.0 Release 8) for more information on User Equipment and Infrastructure.