Definitions for common IoT terminology used on this site.

Glossary item Definition


Second Generation wireless telephone technology. Launched commercially in 1991 to support digital encryption, improved efficiency and data services for mobile (SMS, MMS).


Triple Data Encryption Algorithm. A cryptographic symmetric-key block cipher that increases security against brute force attacks by applying the DES cipher algorithm three times to each data block.


Third Generation wireless telephone technology. Launched commercially in 1998 to support faster data rates (at least 200 kbit/s) which allows wireless video calls and mobile TV.


Third Generation Partnership Project. A collection of standards organisations that develop and define the protocol specifications for mobile telecommunications.


Fourth Generation wireless telephone technology. Launched in 2008 to provide broadband data rates for mobile devices over an IP-based (packet-switched) network infrastructure.


Fifth Generation wireless telephone technology. Launched in 2019 to support a wider frequency spectrum including millimetre wave frequencies, ultra-high data rates, low latency and a large number of devices for M2M and IoT applications.


Technical standard defined by the Institute of Electrical and Electronics Engineers (IEEE) to define the operation of low-rate wireless personal area networks.


Acknowledgement. Control character that acknowledges receipt of a data packet on a TCP connection.


Asymmetric Digital Subscriber Line. Data communications technology that enables faster data transmission over copper telephone lines with a greater emphasis on download compared to upload.


Advanced Encryption Standard (also known as Rijndael). Standard that encrypts electronic data using the same key for both encryption and decryption. This standard supersedes the previously used DES standard.


Advanced Metering Infrastructure. Architecture for automated, two-way communication between a smart utility meter (with an IP address) and a utility company.


Proprietary (but open access) multicast wireless sensor network technology, designed by ANT Wireless, focused on health and fitness.


Application Programming Interface. Method of communication between software components that enables one software system to use services from another.


An Access Point Name (APN) defines the network path between a mobile network and an IP network (the public internet or a private network, for example, Eseye's MPLS network). Each Eseye APN consists of:


Address Resolution Protocol. Protocol that maps the data link layer address (typically MAC address) to a network address (typically IPv4 address) of hardware in a network.


American Standard Code for Information Interchange. Text encoding that represents each alphanumeric or special character as a 7-bit binary number.


Active Server Pages. Microsoft’s first server-side script engine that enables dynamically-generated and interactive web pages.


Amazon Web Services. Cloud computing platform for on demand processing, data storage and additional software services provided through APIs.

Backhaul The process of sending data from a transport network (in the radio access network) back to the operator's core network.


Number of distinct symbol changes (signalling events) made to the transmission medium per second in a digitally modulated signal or a line code. Measured in symbols per second (symbol rate) or pulses per second (modulation rate).


Bit Error Rate. The percentage of bits with errors when compared to the total number of bits that have been transmitted, received or processed over a given time period.


Border Gateway Protocol. Routing protocol that transfers data and information between different host gateways, the Internet or autonomous systems.


Bluetooth Low Energy (also known as Bluetooth Smart). Wireless personal area network technology, designed by the Bluetooth Special Interest Group, that offers up to 1 Mbps transmission rates and up to 100 metres range.

Bootstrap profile

(Also known as provisioning profile). Profile that enables an eUICC-enabled device, when it first starts, to access a cellular network. When using Eseye's multi-IMSI AnyNet+ SIM, the bootstrap profile can support multiple cellular networks.

For more information, see Bootstrap Profile.


Wide bandwidth data transmission system that supports simultaneous transmission of multiple frequencies over a single cable to enable higher data transmission rates.


Business Support Systems. Components that a mobile network operator uses to run its business operations towards customers. Together with operations support systems they are used to support various end-to-end telecommunication services.


Customised Applications for Mobile networks Enhanced Logic. Set of standards designed to work on GSM networks to enable services for roaming subscribers.


Code Division Multiple Access. Channel access method that enables multiple transmitters to simultaneously send information over a single communications channel.


Cellular Digital Packet Data. Specification for utilising unused bandwidths (in the 800 to 900 MHz range) to transfer data at speeds up to 19.2 Kbps.


The European Committee for Standardisation. Public standards organisation whose mission is to foster the economy of the European Union in global trading.


European Committee for Electro technical Standardisation. Standards organisation responsible for European standardisation in the area of electrical engineering.


Challenge-Handshake Authentication Protocol. Protocol that authenticates a user or network host to an authenticating entity (for example, an Internet service provider) whilst providing protection against replay attacks by the peer.

Cloud computing

Network of remote servers (hosted online) that store, manage, and process data.


Constrained Application Protocol. Designed for low memory and low power devices, this transport layer protocol is based on UDP but also works with TCP and SMS. CoAP interfaces with other IP protocols through simple proxies, using binary coded headers to exploit bandwidth with higher efficiency. All resources are represented on a unique address on a server called the URI, and requests for data are sent to this address.


Cyclic Redundancy Check. Hash function that detects errors and accidental changes to digital computer data. It is commonly used in digital telecommunications networks and storage devices such as hard disk drives.


DASH7 Alliance Protocol. Open source wireless sensor and actuator network protocol that operates in the 433 MHz, 868 MHz and 915 MHz unlicensed bands. For example, the Industrial, Scientific and Medical (ISM) band and Short Range Device (SRD) band.


Database Management System. Software application that interacts with the user, other applications, and the database itself to capture and analyse data. A general-purpose DBMS is designed to allow the definition, creation, querying, update, and administration of databases.


Data Circuit-terminating Equipment. Device that sits between the data terminal equipment (DTE) and a data transmission circuit.


Distributed Denial of Service. The intentional paralysing of a computer network by flooding it with data sent simultaneously from multiple computers.


The device can no longer use the SIM to access the mobile network.


Data Encryption Standard. Outdated method of symmetric key data encryption replaced by 3DES and more recently AES.


Dynamic Host Configuration Protocol. Client-server protocol that automatically provides an Internet Protocol host with its IP address and other related configuration information.


Proprietary wireless mesh networking topology (developed by Digi) that enables all nodes to simultaneously act as a transmitter, receiver, and repeater.


Digital Signature Algorithm. A standard to create digital signatures introduced in 1991 by the National Institute of Standards and Technology.


Digital Subscriber Line. Family of technologies used to transmit digital data over telephone lines.


Data Terminal Equipment (also known as tail circuits). An end instrument that converts user information into signals, or reconverts received signals. A DTE device communicates with the data circuit-terminating equipment (DCE).

DTLS Datagram Transport Layer Security. A communications protocol that provides extra security for messages (datagrams) that are sent from an application to other hosts on an IP network.


Extensible Authentication Protocol. Authentication framework that extends existing authentication methods for use in wireless networks and point-to-point connections.


Enhanced Data rates for GSM Evolution. Evolution of GPRS technology (built on 2G) that increases data rates to speeds of 120-384Kbps.


eUICC identifier. Unique 32-digit number, which is defined by the eUICC manufacturer (EUM).


Equipment Identity Register. A core network database that contains a list of IMEIs (devices) that is independent of the IMSI (subscriber) or MSISDN (phone number). This enables the network operator to block devices that have been reported as stolen even if a different SIM is inserted into the stolen device. The operator can also restrict IMEIs (devices) to only work with specific IMEIs (SIMs).

Embedded software

Instruction code that runs on hardware micro-controllers to perform specific low-level functions, often without use of an operating system.


European standards documents that have been ratified by one of the three European standards organisations: CEN, CENELEC or ETSI.


Evolved Packet Core. Core network infrastructure in an LTE network including the serving gateway, HLR, MME and PDN gateway.


The GSMA embedded SIM Remote Provisioning Architecture that enables remote SIM provisioning and management.

For more information, see About eSIM.


Collection of computer networking technologies and standards that define local and wide area networks.


European Telecommunications Standards Institute. Standards organisation in the telecommunications industry (equipment manufacturers and network operators) in Europe.


embedded Universal Integrated Circuit Card. Software component of eSIM that stores multiple network profiles which can be provisioned and managed over-the-air (OTA).

For more information, see About eUICC.


eUICC Manufacturer. Accredited organisations that manufacture and personalise eUICC SIMs.


Evolution-Data Optimised. Evolution of the CDMA2000 telecommunications standard that was designed to transmit data using radio signals (typically for broadband Internet access) alongside a wireless carrier's voice services.


Frequency Division Duplexing. Transmission method where the transmitter and receiver operate at different carrier frequencies, which enables them to transmit data at the same time.


Fixed Dialling Number. Service mode of a GSM phone's SIM card that restricts outgoing calls to only numbers (or prefixes) added to an FDN list.


File Transfer Protocol. Standard network protocol for transferring files from a client/server to a server/client over a TCP-based network, such as the Internet.


Device that receives information from many points on a network and transmits information to another network.


General Data Protection Regulation – a law that requires organisations to adhere to privacy and security standards when targeting and collecting data related to people in the EU. Failure to adhere to these standards can result in heavy financial penalties.


Gateway GPRS Support Node. Part of the cellular GPRS network responsible for interworking between the GPRS network and external packet switched networks, such as the Internet and X.25 networks.

GlobalPlatform An organisation that creates and publishes specifications for secure chip technology.


General Packet Radio Service. Packet-oriented mobile data service on the 2G and 3G cellular networks.


Global System for Mobile communication. Standard that defines the protocols for use in 2G mobile networks and devices.

Hardware Acceleration

Use of computer hardware to perform some functions faster than possible in software running on a more general purpose CPU.


Home Location Register. The network operator's database of mobile subscriber information including lists that match phones, phone numbers, user accounts and service plan information.

Home network

The active profile or IMSI provider, which provides connectivity and other services to the IoT device.


Home Subscriber Server. Subscriber database, located within the IP Multimedia Subsystem (IMS), that provides details of the subscribers to other entities within the network.


Hypertext Transfer Protocol. Application layer protocol for transferring distributed, collaborative, hypermedia information systems. It is the foundation of data communication for the World Wide Web.


Hypertext Transfer Protocol Secure (also called HTTP over TLS/SSL). Application layer protocol for secure communication over a computer network. It is widely used on the Internet and consists of communication over HTTP within a connection encrypted by TLS or SSL.


Integrated Circuit Card Identifier. Unique identifier (up to 20 characters in length) for a SIM or SIM profile (when using an eUICC SIM).


Internet Control Message Protocol. Supporting protocol used by network devices (like routers) to send error messages and operational information.


Internet Group Management Protocol. Communications protocol used by hosts and adjacent routers on IPv4 networks to establish multicast group memberships.


Internet Key Exchange (also known as IKEv2). Part of the IPsec protocol suite responsible for setting up security associations.


Internet Message Access Protocol. Internet standard protocol used by email clients to retrieve e-mail messages from a mail server over a TCP/IP connection.


The International Mobile Equipment Identity number that identifies the device to which the SIM is currently connected.


The unique International Mobile Subscriber Identity number that identifies a cellular network subscriber. The network operator that provided the IMSI uses it to authenticate a SIM (and the IoT device containing the SIM) on the network.


Proprietary protocol that uses powerline and radio frequency (RF) to communicate with devices. When using the Insteon protocol, all devices can repeat messages.


An interconnect integrates Eseye and a partner MNO, using the following components:

  • Eseye-distributed SIM profile or IMSI
  • APN connection into an Eseye PoP, via a packet gateway
  • MNO-supplied APIs for provisioning, SMS, and so on


Internet of Things. Inter-networking of physical devices embedded with software/sensors/actuators to enable network connectivity used to collect and exchange data between the devices.


Internet Protocol. Set of digital message formats and rules for exchanging messages between computers across a single network or a series of interconnected networks.

IP filtering

Mechanism to decide which IP datagrams are processed normally and which are discarded as if never received.

IP Multicast

Method of sending IP datagrams to a group of interested receivers in a single transmission. The method is an IP-specific version of multicast networking.


Internet Protocol Security. Protocol suite for secure IP communications that authenticates and encrypts each IP packet of a communication session. It includes protocols for establishing mutual authentication between agents at the beginning of the session and negotiation of cryptographic keys for use during the session.


Internet Protocol Version 4. Connectionless protocol used on packet-switched networks. It operates on a best effort delivery model and does not guarantee delivery or assure proper sequencing or avoidance of duplicate delivery.


Internet Protocol Version 6. Communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet.


Integrated Services Digital Network. Set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network.


Integrated SIM. A non-removable eUICC SIM that is integrated alongside the processor and modem on a system on a chip (SoC) to reduce power consumption, footprint, and manufacturing costs.

ISM band

Industrial, Scientific and Medical band. An unlicensed part of the radio frequency (RF) spectrum used for general purpose data communications.


International Organisation for Standardisation. International standard-setting body composed of representatives from various national standards organisations to promote worldwide proprietary, industrial and commercial standards.


Specification for an information security management system, covering all legal, physical and technical controls involved in an organisation's information risk management processes.


JavaScript Object Notation. Lightweight data interchange format that is human-readable and machine-parseable.


Local Area Network. A computer network that interconnects computers within a limited area and locally manages its network equipment and interconnects.


Link Control Protocol. Part of the point-to-point protocol (PPP) suite. In setting up PPP communications, both the sending and receiving devices send out LCP packets to determine the standards of the ensuing data transmission.


Lightweight Directory Access Protocol. Software protocol that enables anyone to locate organisations, individuals and other resources (files or devices) in a network, both on the public Internet or a private Intranet.


Process of connecting a device to a local network in order to avoid roaming issues or improve connectivity and/or performance.

Loopback interfaces

Logical, virtual interface in a router that never goes down, unless the entire router goes down.


Long Range Wide Area Network. Specification intended for wireless battery operated devices in regional, national or global network.

Link budget

Accounting of all of the power gains and losses that a communication signal encounters at connection points in the system, such as from antennas, structural attenuation, propagation loss and so on.


Low-Power Wide Area. Networks that are built specifically for M2M communications and offer long-range and low-power consumption.


Low-Power Wireless Sensor Network. Group of spatially distributed, independent devices that collect data by measuring physical or environmental conditions with minimal power consumption.


Long Term Evolution. Standard for high-speed wireless communication for mobile phones and data terminals. It increases the capacity and speed using a different radio interface together with core network improvements.


LTE-MTC (machine-type communications). More energy efficient part of the Long Term Evolution (LTE) system that uses features such as extended discontinuous repetition cycles (eDRX) for machine-type communications.


Machine to Machine. Direct communication between devices using any communications channel, including wired and wireless. For example industrial instrumentation that enables a sensor or meter to communicate data to a software application for payment processing.


Media Access Control (also known as Medium Access Control). Part of the data link layer that enables multiple hardware terminals to communicate within a network incorporating wired, optical or wireless transmission medium.


Mobile Application Part. An SS7 application layer protocol that enables communication between GSM, UMTS and GPRS core network nodes (HLR, VLR, MSC, EIR, SMSC and SGSN) in order to provide services to users.


Mobile Country Code. A three digit unique identifier for a country. The MCC is also the first part of the IMSI. For more information, see Mobile country codes.

Messaging API

Messaging Application Programming Interface (also known as Messaging Gateways). Software that transmits data from one protocol to another. For example, Eseye provide an SMS Messaging gateway service.


Machine-to-Machine Form Factor SIM. An integrated circuit permanently soldered into an IoT device. It has eight electrical pins, which are exactly the same as the eight gold contacts on removable SIMs.


Mobile Network Code. A two or three digit unique identifier for a home network within a country, which is identified by the MCC. The MNC is the second part of the IMSI, after the MCC. For more information, see Mobile network codes listed by country.


Mobile Network Operator. Telecommunications service provider that provides wireless voice and data communication to its subscribed mobile users.


Multi-protocol Label Switching is a high-speed, protocol-independent networking technology that routes data traffic along preconfigured paths, to handle forwarding over private wide area networks. MPLS assigns labels to each data packet, rather than network addresses, to control the path each packet follows.


Message Queuing Telemetry Transport. Designed for low bandwidth, high latency networks, this lightweight machine-to-machine protocol uses brokers that receive all communications for relaying between clients. Devices publish and subscribe to content within the broker.


Message Queuing Telemetry Transport Secured. See MQTT.


Mobile Switching Center. The part of operator's core 2G RAN that is responsible for routing voice and SMS services. The MSC connects to other core network components (HLR, VLR) and the base station subsystem (BSS) which is responsible for sending radio signals to the device.


Mobile Station International Subscriber Directory Number. Unique identifier for a mobile phone number that includes an international country code and a national destination code identifying the subscriber’s operator.


A SIM that stores IMSIs from multiple MNOs, and can switch between networks without physically changing the SIM.


Mobile Virtual Network Enabler. Organisation that provides network infrastructure and services to support mobile virtual network operators.


Mobile Virtual Network Operator. Mobile network operator that does not own the wireless network infrastructure that it uses to provide services to its subscribers.


Network Address Translation. Method to map the many private IP addresses within a secure subnet to a single public IP address and port number for communication across the internet.


Narrow Band Internet of Things. 5G narrow band technology that utilises side bands or unused parts of the GSM spectrum.

Netflow Analysis

NetFlow is a network protocol for collecting IP traffic information and monitoring network traffic. Analysing NetFlow flow data builds a picture of network traffic flow and volume.


Near Field Communication. Low-power, low-speed, short-range radio communication standard that allows two-way communication between endpoints in close proximity.


Network File System. Client/server application that lets a computer user view and optionally store and update files on a remote computer.


Network Function Virtualisation. Process of reconfiguring network nodes for use on virtual machines or cloud computing infrastructure in order to create communications services.


Network Time Protocol. Protocol that synchronises computer clock times, using the Coordinated Universal Time (UTC) format, across a network of computers.


OASIS Open Building Information eXchange Technical Committee. Industry-wide initiative to define XML and Web services-based mechanisms for building control systems.


Online Charging System. Mechanism that enables a service provider to charge their customers.


Open Charge Point Protocol. Protocol that enables communication between electric charging points and management systems.


Original Equipment Manufacturer. Company that produces components that are parts or subsystems of another company’s product.

Operational profile

(Also known as Step 2 profile). eUICC SIM profile with full to access an operator’s network.

For more information, see Operational profile.


Operational Support System. Set of programs that communications service providers use to monitor, control, analyse and manage a telephone or computer network.


Over-The-Air. Transfer of information or power between two or more points that are not physically connected.


A package contains the information required for Eseye to supply, provision and operate SIMs for a customer. It defines commercial data (such as the tariff and billing terms), the available SIM services (such as data, voice, SMS), and the technical provisioning data that is used to activate and operate SIMs.


Personal Area Network. Network of devices operating within the range of an individual person. For example, Bluetooth devices often create consumer PANs.


Password Authentication Protocol. Authentication protocol used by the point-to-point protocol (PPP) to validate users before allowing them access to server resources.


Platform As A Service. Platform that provides services to users of one or more software applications which typically run in the cloud.

PCI compliant

The Payment Card Industry Data Security Standard (PCI DSS) is a set of regulatory requirements for ensuring that all companies that process, store, or transmit credit card information maintain a secure environment.


Policy and Charging Rules Function. Software component in the network that aggregates real-time data and uses rules to apply different policy decisions for each subscriber.


Packet Data Network Gateway. Gateway that connects the external packet data network (PDN) and the evolved packet core (EPC).

PLMN Public Land Mobile Network. A country-specific wireless network operator that provides cellular connectivity, typically using multiple radio access technologies (2G, 3G, 4G, 5G).
PoP Point of Presence. Eseye has multiple PoPs that exist in data centres worldwide, for ingressing and egressing the Eseye network.


Post Office Protocol. Application-layer Internet standard protocol used by local email clients to retrieve e-mail from a remote server over a TCP/IP connection.

Port Forwarding

Port Forwarding (also known as Port Mapping). NAT application that redirects a communication request from one address and port number combination to another while the packets are traversing a network gateway, such as a router or firewall.


Point-to-Point Protocol. Data link (layer 2) protocol that establishes a direct connection between two nodes and provides connection authentication, transmission encryption, and compression.

Private Network

A network that uses private IP address space, following the standards set by RFC 1918 for IPv4, and RFC 4193 for IPv6.

Provision The process of activating a SIM so that it can access network services.

Provisioning profile

See Bootstrap profile .


Public Switched Telephone Network. World's circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication.


Remote Authentication Dial-In User Service. A client-server network protocol that manages user authentication, authorisation and accounting (AAA) for network services.


Quality of Service. Network’s ability to achieve maximum bandwidth and deal with other network performance elements, such as latency, error rate and uptime.


Radio Access Technology. The underlying radio interface that a device uses to connect to a cellular network. A device may support one or more RATs.


Relational Database Management System. Database management system (DBMS) based on the relational model. It is the basis for SQL and for all modern database systems (MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access).


Radio Frequency. Frequency of radio transmissions but is often used more generally to mean 'wireless communication'.


Radio Frequency Identification. Technology that uses strong short-range electromagnetic waves to transmit and receive data in order to identify and track tags attached to objects.

Roaming agreement

A contract that enables one operator to provide service to subscribers (IMSIs) that do not belong to their network. The services available to roaming devices may differ from the services provided by the home network operator.

Roaming agreements are not permanent and may change over time, which can impact subscriber connectivity.


Rivest, Shamir and Adleman. Cryptosystem for public-key encryption that is widely used for securing sensitive data, particularly when being sent over an insecure network such as the Internet.


Remote SIM Provisioning. Secure management of network profiles on eUICC-enabled devices using over-the-air commands.

For more information, see Remote SIM Provisioning.

RSSI Received Signal Strength Indicator. Measurement of the incoming (received) radio signal strength.


Software as a Service (also known as on-demand software). Software licensing and delivery model in which software is licensed on a subscription basis and is centrally hosted.


Software-Defined Networking. Umbrella term encompassing several kinds of network technology aimed at making the network as agile and flexible as the virtualised server and storage infrastructure of the modern data centre.


Device that detects changes in the ambient conditions or in the state of another device or a system, and conveys or records this information.


Secure File Transfer Protocol. Secure version of FTP that facilitates data access and data transfer over a SSH data stream.


Serving GPRS Support Node. Main component of the GPRS network that handles all packet switched data within the network, e.g. the mobility management and authentication of the users.


SIM Information and Account Management. Eseye's online web portal for SIM management.

Renamed to Infinity Classic.


Subscriber Identification Module. Integrated circuit that is responsible for securely storing data including the ICCID, IMSI and authentication keys. The data is used to identify and authenticate subscribers on mobile devices.


Stock Keeping Unit. Unique identifier for a specific product or service for sale.


Subscription Manager Data Preparation. The network system that operators use to securely store network profiles.

For more information, see Subscription Manager – Data Preparation (SM-DP).


Subscription Manager Secure Routing. The network system responsible for delivering encrypted operator credentials to the SIM and, once the credentials are installed, remotely provisioning the SIM.

For more information, see Subscription Manager – Secure Routing (SM-SR).


Short Message Service. Text messaging service component of most telephone, World Wide Web, and mobile telephony systems.


Short Message Service. Text messaging service component of most telephone, World Wide Web, and mobile telephony systems.


Short Message Service Center. The network component located in an operator's core network that is responsible for receiving, storing, forwarding and sending SMS messages.


Command-line application that sends SMS messages to a list of phone numbers located in a file.


Simple Mail Transfer Protocol. Application protocol for sending and receiving emails.


Simple Network Management Protocol. Network management protocol that collects information and configures network devices on an IP network.


Simple Object Access Protocol. Protocol for exchanging structured information in the implementation of web services in computer networks.


Structured Query Language. Special-purpose programming language designed for managing data held in, or stream processing in a relational database management system (RDBMS).


Signalling System Number 7. Signalling protocols that set up and terminate telephone calls.


Secure Shell. A protocol that initiates secure text-based shell sessions on remote machines .


Service Set Identifier. Unique identifier for a wireless network.

Stateful Firewall

A network firewall that tracks the operating state and characteristics of network connections traversing it and distinguishes legitimate packets for different types of connections.

Step 2 profile

See Operational profile.

Structure attenuation

The loss in intensity of radio waves through a medium (for example radio waves through a brick wall). Structure attenuation can slow data transmission in the IoT.


Signal Transfer Point. Router that relays SS7 messages between signalling end-points and other signalling transfer points (STPs).


Transmission Control Protocol/Internet Protocol. Standard protocol for internet-based communications.


Time Division Multiple Access. Archaic 2G mobile phone system. Existing networks are mostly replaced by GSM/GPRS or CDMA2000 technologies.


Session layer protocol used on the Internet or local area networks to provide a bidirectional communication using a virtual terminal connection.


Trivial File Transfer Protocol. Internet software utility used to transfer files.


Transport Layer Security. Cryptographic protocol that provides communications security over a computer network. Several versions of the protocol find widespread use in applications such as web browsing, email, Internet faxing, instant messaging, and VoIP.


Time To Live. A timer value included in packets sent over TCP/IP-based networks, which specifies how long recipients can hold or use the packet and its included data before expiring and discarding the packet or data.


For DNS – the time, for each DNS record, that specifies how long a resolver can take to cache (or remember) the DNS query before the query expires.


Universal Asynchronous Receiver/Transmitter. Computer hardware device for asynchronous serial communication in which the data format and transmission speeds are configurable.


User Datagram Protocol. Alternative communications protocol to TCP. It is primarily used for establishing low-latency, loss tolerating connections between applications on the Internet.


Universal Integrated Circuit Card. Hardware containing the SIM software and applications that enable a device to access cellular networks.


Universal Mobile Telecommunications System. 3G mobile cellular system for networks based on the GSM standard. UMTS uses W-CDMA radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators.


Uniform Resource Locator (also known as a web address). Reference to a web resource that specifies its location on a computer network and a mechanism to retrieve it.


Unstructured Supplementary Service Data. GSM-only (not supported in 4G/5G) communication protocol that sends data between a mobile phone and an application running in the network. Used to query information and generate services.


Coordinated Universal Time. A universal standard for time (defined in ITU-R TF.460-6) that regulates clocks. UTC time is mapped to geographical timezones but does not change for regional adjustments such as daylight savings.


Ultra-wide band. Technology that uses short, narrow pulses and can be an attractive option for asset tracking and fleet/ inventory management.


Virtual Evolved Packet Core. A framework to virtualise the functionality provided by the evolved packet core (EPC).


Visitor Location Register. A database, located in the operator's core network, that contains the devices connected to a specific base station. Device can only be listed in the VLR associated to the base station to which the device is connected.


Virtual Machine. Software system that runs on one computer and emulates the functionality of a different physical computer on the computer running the virtual machine.


Virtual Network Function. Network services running on virtualised computing platforms.


Voice over Internet Protocol. Set of rules that enable use of the Internet for telephone or videophone communication.


Network Address Translation. Method to map the many private IP addresses within a secure subnet to a single public IP address and port number for communication across the internet.


Virtual Router Redundancy Protocol. Networking protocol that automatically assigns available IP routers to participating hosts.


Wide Area Network. Telecommunications network or computer network that extends over a large geographical distance.


Wideband Code Division Multiple Access. 3G standard that employs the direct-sequence code division multiple access channel access method and the FDD method to provide high-speed and high capacity service.


Set of LPWAN open wireless technology standards for exchanging data between a base station and low powered devices.


Wired Equivalent Privacy. Security protocol, specified in the IEEE Wi-Fi standard, 802.11b, that is designed to provide a WLAN with a level of security and privacy comparable to what is usually expected of a wired LAN.


Wireless technology that enables computers, smartphones, or other devices to connect to the Internet or communicate with one another wirelessly within a particular area.


Worldwide Interoperability for Microwave Access is a family of wireless communication standards based on the IEEE 802.16 set of standards, which provide multiple physical layer and MAC options.


Wireless Local Area Network. Wireless computer network that links two or more devices using a wireless distribution method (often spread-spectrum or OFDM radio) within a limited area such as a home, school, computer laboratory, or office building.


WiFi Protected Access (WPA) and WiFi Protected Access II (WPA2). Security protocols and security certification programs developed by the WiFi Alliance to secure wireless computer networks.


WiFi Protected Access Pre-Shared Key. Security mechanism that authenticates and validates users on a wireless LAN or WiFi connection. It is a variation of the WPA security protocol. WPA-PSK is also known as WPA2-PSK or WPA Personal.


World Wide Web (also known as the web). An information space where documents and other web resources are identified by Uniform Resource Locators (URLs), interlinked by hypertext links, and can be accessed via the Internet.


Open global standard for wireless technology designed to use low-power digital radio signals for personal area networks. ZigBee operates on the IEEE 802.15.4 specification.


Protocol for communication among devices used for home automation. It uses radio frequency (RF) for signalling and control.