Glossary of Terms for IoT SIM Cards & IoT Devices

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• 2G
  Second Generation mobile network, refers to the first digital cellular network standard, launched in the early 1990s. It replaced the older 1G analog systems and marked the beginning of digitized voice communication over mobile networks. Still relevant for low-bandwidth IoT, but being phased out in many regions.
• 3G
  Third Generation mobile network, refers to the third generation of wireless mobile telecommunications technology, standardized by 3GPP (Third Generation Partnership Project). Launched in the early 2000s, 3G was a major leap forward from 2G, enabling mobile broadband and richer mobile internet experiences. It laid the groundwork for today's connected world but is now being phased out in many regions. 3G was used extensively in early and mid-generation IoT and M2M deployments, including:
  • Vehicle telematics
  • ATMs and payment terminals
  • Mobile surveillance
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  • Smart agriculture (aka AgTech)
  • Remote healthcare
  For IoT, modern projects should transition to 4G/5G or LPWAN alternatives.
• 3GPP (3rd Generation Partnership Project)
  A global collaboration between groups of telecommunications standards organizations, known as Organizational Partners. It develops and maintains technical specifications and standards for 2G, 3G, 4G LTE, LTE-Advanced, 5G, and beyond. 3GPP plays a crucial role in IoT communications by:
  • Defining low-power wide-area network (LPWAN) standards like NB-IoT and LTE-M
  • Ensuring interoperability across global mobile networks
  • Providing security and authentication frameworks for SIM-based connectivity
• 4G
  Fourth Generation mobile network, is a high-speed wireless communication standard for mobile devices and wireless IoT applications. Introduced around 2009–2010, 4G was designed to deliver true mobile broadband, offering dramatically improved data speeds and network efficiency compared to 3G.
  4G is widely used in modern IoT deployments due to its global reach, low latency, and capacity for real-time data transmission. IoT Use Cases with 4G:
  • Smart cities and infrastructure (e.g., traffic systems, smart lighting)
  • Live video streaming from security cameras
  • Remote health monitoring
  • Connected vehicles and telematics
  • Industrial automation and robotics
• 5G
  Fifth Generation mobile network, is the latest global wireless standard designed to connect everything — people, devices, machines, and systems — with ultra-high speed, low latency, and massive capacity. It builds on the strengths of 4G LTE but introduces entirely new capabilities tailored for the Internet of Things (IoT)
  5G is a game-changer for IoT because it supports:
  • Massive Machine-Type Communication (mMTC) For smart cities, agriculture, and industrial IoT
  • Ultra-Reliable Low-Latency Communication (URLLC) For autonomous vehicles, robotic surgery, and remote control systems
  • Enhanced Mobile Broadband (eMBB) For AR/VR, live 4K/8K video, and immersive experiences
  
  Example IoT Applications:
  • Smart factories (Industry 4.0)
  • Autonomous vehicles
  • Remote surgery
  • Real-time drone navigation
  • Smart grids and utilities
  • Massive-scale sensor networks
  Ultra-fast, ultra-reliable, ultra-connected. It’s not just faster — it’s the foundation for next-generation IoT, automation, AI, and global connectivity. From smart cities to remote robotic surgery, 5G will reshape industries and daily life.
• 5G NR (5G New Radio)
  This is the RAT developed by the 3GPP that offers faster speeds, more efficient use of network spectrum and better latency than other RAT's like 4G LTE and GSM.
• 5G RedCap (5G Reduced Capability)
  Otherwise referred to as 5G NR-Light, this is a protocol that lies between 4G LTE and eMBB 5G and offers better performance than 4G without the power consumption of eMBB 5G.

A

• A2P SMS (Application-to-Person SMS)
  A method of sending and receiving an SMS message to a SIM card/device using an application like such as directly through the OneSimCard IoT OSCAR Management Portal or API Commands (as opposed to P2P SMS)
• APN (Access Point Name)
  The network path for connecting a device to the internet using a mobile network. Custom APNs are often used for secure IoT deployments.
• API (Application Programming Interface)
  A software interface that allows applications and systems (e.g., IoT platforms and SIM management systems) to communicate with each other.
• Antenna
  A component in IoT devices that sends and receives wireless signals for cellular, Wi-Fi, or Bluetooth communication.
• AT commands (short for Attention Commands)
  Text-based instructions used to communicate with and control modems and wireless modules, including those found in IoT devices. These commands enable external systems (like microcontrollers or computers) to interact with a modem for tasks like sending SMS, initiating data connections, querying network status, and more.
  Key Characteristics of AT Commands:
  • Command Prefix - All AT commands begin with AT (short for “Attention”)
  • Human-Readable - Text-based, easy to type and interpret
  • Versatile Control - Used to configure, monitor, and operate GSM/3G/4G/LTE/5G modems Device Agnostic Supported by many modem types, from USB dongles to embedded cellular modules
  • Synchronous - Sent via a serial interface (UART, USB, etc.), and the device responds with status or result codes
  Common AT Command Examples:
  • AT - Test command; checks communication with modem (should return OK)
  • AT+CSQ - Check signal quality
  • AT+CGATT? - Check if the device is attached to the packet domain
  • AT+CMGF=1 - Set SMS mode to text
  • AT+CMGS="+1234567890" - Send an SMS message
  • AT+CREG? - Query network registration status
  • AT+CGDCONT=1,"IP","internet" - Define PDP context (used to set APN for mobile data)
  AT Commands in IoT
  AT commands are widely used in IoT development and device integration, particularly when working with cellular modules such as:
  • Quectel
  • Telit
  • u-blox
  • SIMCom
  • Sierra Wireless
  These commands allow IoT developers to:
  • Set up cellular data connections
  • Send/receive SMS alerts
  • Query network status and strength
  • Manage SIM card and operator profiles
  • Monitor battery and module health
  • Communication Method
  AT commands are typically sent over:
  • UART (Serial Port)
  • USB
  • TCP/IP (via Telnet or virtual ports in advanced modules)
  They can be scripted and automated in microcontroller code, Python scripts, or IoT platform SDKs.
  Summary
  AT Command = A simple, text-based way to control modems and cellular modules Crucial in IoT development, prototyping, and diagnostics, AT commands offer direct, low-level control of wireless connectivity in cellular IoT applications.

B

• BLE (Bluetooth Low Energy)
  A wireless communication protocol designed for short-range, low-power communication. Common in wearables and smart home devices.
• Bandwidth
  The capacity of a connection to transmit data, measured in bits per second. Higher bandwidth is required for devices that stream or transfer large data.
• Base Station
  A fixed communication point in a cellular network that connects to mobile and IoT devices in a specific area.

C

• Cellular Connectivity
  Wireless communication through 2G/3G/4G/5G networks. IoT SIM cards enable devices to access cellular networks globally.
• Cloud Computing
  The delivery of computing services (storage, databases, processing) over the internet. Used to store and process data from IoT devices.
• Coverage
  The geographical area where an IoT SIM can connect to a network. Global IoT SIMs offer broader coverage across multiple carriers.

D

• Data Plan
  The allocation of data for a SIM card. IoT deployments often use pooled or pay-as-you-go data plans.
• Device Management
  The monitoring and remote control of IoT devices, including firmware updates and diagnostics.
• Dual SIM / Multi-IMSI
  Technology allowing devices to switch between networks using multiple IMSIs or SIMs for redundancy and better coverage.

E

• eSIM (Embedded SIM)
  A reprogrammable SIM embedded in the device itself, allowing remote provisioning and multiple carrier profiles.
• Edge Computing
  Data processing that happens near the device (at the "edge" of the network) to reduce latency and bandwidth usage.
• Encryption
  The process of converting data into a secure format. Used to protect data transmitted between IoT devices and the cloud.
• eUICC (Embedded Universal Integrated Circuit Card)
  The programmable component inside an eSIM (embedded SIM), designed to securely store and manage multiple mobile network profiles. Unlike traditional SIM cards, an eUICC allows remote provisioning and switching of operators without physically changing the SIM card.

F

• Firmware
  Low-level software that controls hardware functions in IoT devices. Often updated remotely over-the-air (OTA).
• Form Factor
  The physical size and shape of a SIM card or IoT device. SIMs come in standard, micro, nano, and embedded (MFF2) sizes.

G

• Gateway
  A device that bridges local networks (Bluetooth, Zigbee) with the internet. Many use IoT SIM cards for cellular backhaul.
• Global SIM
  A SIM that supports multiple carrier profiles and can operate in over 100+ countries, often without steering to preferred networks.
• Geofencing
  The use of GPS or RFID to define virtual boundaries. IoT devices can trigger alerts when crossing these boundaries.

H

• Hardware Security Module (HSM)
  A physical device that safeguards digital keys used for authentication and encryption in IoT communications.
• HLR (Home Location Register)
  A mobile core network database that contains details about each SIM and its subscribed services.

I

• IC (Integrated Circuit)
  A complete electronic circuit miniaturized onto a chip, enabling the compact, powerful, and efficient electronics that power the modern digital and connected world — especially in IoT systems and mobile communications. Examples include the "gold" contact area on an IoT SIM Card, a microprocessor, an MFF2 eSIM card, etc.
• ICCID (Integrated Circuit Card Identifier)
  A unique 19-20 digit number used to identify a SIM card globally.
• IMEI (International Mobile Equipment Identity)
  A unique 15-digit number assigned to every mobile device that connects to a cellular network, including smartphones, tablets, and IoT devices with cellular modems.
  Key Functions of IMEI:
  
  • Device Identification - Uniquely identifies a physical device on a mobile network — like a fingerprint for your phone or IoT device
  • Security & Anti-Theft - Carriers can blacklist a stolen device using its IMEI, preventing it from accessing networks
  • Device Management - Used by mobile network operators for diagnostics, tracking, and compliance
  • Not Tied to SIM - Unlike IMSI, which identifies the SIM card, IMEI identifies the hardware itself
  IMEI Format
  A standard 15-digit IMEI is typically structured as NNNNNN–SSSSSS–C:
  
  • NNNNNN: Type Allocation Code (TAC) – identifies the device model and origin
  • SSSSSS: Serial number – unique to the individual device
  • C: Check digit – used for validation
  IMEI in IoT
  In IoT contexts, IMEI is essential for:
  • Fleet tracking and remote monitoring
  • Authentication and device-level security
  • Pairing with SIM/ICCID for secure SIM management
  • Monitoring performance and usage in IoT dashboards
  IMEI Blacklisting
  If a device is reported stolen or involved in fraud, the IMEI can be blacklisted in global databases (e.g., GSMA IMEI DB), preventing it from operating on mobile networks.
  Summary
  IMEI = Unique identifier for mobile devices and is used to track, secure, and manage physical cellular-connected devices — especially important in IoT, asset tracking, and fleet control.
• IMSI (International Mobile Subscriber Identity)
  A unique identifier stored in the SIM card used to connect to mobile networks.
• IoT (Internet of Things)
  A network of interconnected physical devices that communicate and exchange data over the internet or other networks.
• IP Address
  A numerical label assigned to each device in a network. Static IPs are often used in IoT for consistent access.

J

• Jitter
  The variation in packet arrival time in network communication. Critical for real-time IoT applications like VoIP or live monitoring.

L

• Latency
  The time it takes for data to travel from source to destination. Low latency is crucial for mission-critical IoT systems.
• LoRa / LoRaWAN
  A low-power, long-range wireless communication technology used for IoT devices in agriculture, logistics, and smart cities.

M

• M2M (Machine-to-Machine)
  Direct communication between devices without human involvement, typically over cellular networks.
• MNO (Mobile Network Operator)
  MNO stands for Mobile Network Operator. It refers to a telecommunications company that owns and operates the infrastructure necessary to provide cellular network services — such as voice, SMS, and mobile data — to end users and connected devices, including those in IoT deployments.
• MO SMS (Mobile Originating SMS)
  In IoT, this is an SMS being sent from a device with a SIM card inserted in it.
• Module
  A self-contained unit within an IoT device that provides a specific function, such as cellular connectivity or GPS.
• MQTT (Message Queuing Telemetry Transport)
  A lightweight messaging protocol ideal for constrained devices and unreliable networks.
• MT SMS (Mobile Terminating SMS)
  In IoT, this is an SMS being sent to a device with a SIM card inserted in it.
• Multi-IMSI (Multi–International Mobile Subscriber Identity)
  Refers to a technology that allows a single SIM card or eSIM to store and use multiple IMSI profiles, enabling the device to dynamically switch between mobile networks. Each IMSI represents a unique mobile subscription tied to a specific carrier, country, or region. It provides intelligent, flexible, and cost-effective connectivity, especially for globally deployed IoT devices, by allowing automatic, remote switching between multiple carrier identities built into a single SIM or eSIM.
• MVNO (Mobile Virtual Network Operator)
  A mobile service provider that doesn't own the network, but offers custom connectivity solutions — often with more flexibility, better pricing, and multi-network capabilities. In IoT, MVNOs like OneSimCard IoT play a crucial role in enabling global, scalable, and reliable device connectivity.

N

• NB-IoT (Narrowband IoT)
  A cellular LPWAN technology optimized for low-power, low-data, long-battery-life IoT applications.
• Network Steering
  The practice of forcing a SIM to prioritize specific carrier networks. Non-steered SIMs automatically choose the best available signal.
• Node
  Any active device in an IoT network that can send, receive, or route data.

O

• OTA (Over-the-Air)
  Remote updating or configuration of IoT devices and SIMs without physical access.
• Operator Profile
  The configuration data that allows an eSIM to connect to a specific mobile network operator.

P

• P2P SMS (Person-to-Person SMS)
  
• Private APN
  A secure and isolated path through a mobile network used to connect IoT devices to private cloud services.
• Provisioning
  The process of preparing and configuring an IoT SIM or device for deployment, often done remotely.

Q

• QoS (Quality of Service)
  The measurement of performance in a network service, including bandwidth, latency, and error rates. Critical for applications like telehealth.

R

• Roaming
  The ability of a SIM card to connect to a different carrier network when outside its home network, essential for global IoT solutions.
• Remote SIM Provisioning (RSP)
  The process of activating or switching eSIM profiles over-the-air without physical SIM swaps.

S

• Sensor
  A component that detects and responds to input from the environment, such as temperature, motion, or light.
• SIM (Subscriber Identity Module)
  A small chip — either removable (2FF, 3FF, 4FF form factors) or embedded (MFF2 form factor)— used in mobile devices and IoT hardware to identify and authenticate the subscriber on a mobile network. Without a SIM, a device cannot connect to a cellular network to use voice, SMS, or mobile data services.
• SIM Management Platform/Portal
  A web-based platform that allows businesses, developers, and IoT operators to remotely manage, monitor, and control large fleets of SIM cards or eSIMs used in IoT (Internet of Things) and M2M (Machine-to-Machine) deployments. It serves as the central hub for overseeing SIM lifecycle operations — from activation to suspension, diagnostics, data usage tracking, and provisioning — across thousands or even millions of devices.
• Static IP Address
  A permanent IP address assigned to a device, often used in security or remote monitoring applications.
• Steering SIM Card (Also known as Network Steering)
  A Steering SIM card is a type of SIM that is programmed to prioritize specific mobile networks based on agreements or preferences set by the SIM provider or Mobile Virtual Network Operator (MVNO). This process is called network steering, where the SIM card "steers" the device toward predefined preferred networks — even if they are not the strongest or fastest available at that location.
  OneSimCard IoT is a No Steering operator. We do not steer network traffic.

T

• Telemetry
  The automated communication of measurements and data from remote devices to a receiving system.
• Throttling
  The intentional slowing of data speeds after a certain usage threshold is reached in a data plan.

U

• UICC (Universal Integrated Circuit Card)
  A smart card used in mobile terminals that supports multiple applications like SIM, USIM, and ISIM.
• Usage Monitoring
  Tracking data, SMS, and voice usage of IoT SIM cards in real-time to prevent overages and detect issues.

V

• VPN (Virtual Private Network)
  An encrypted connection over the internet that ensures secure communication between IoT devices and backend servers.
• VoLTE (Voice over LTE)
  Enables voice services over LTE networks, sometimes supported in IoT devices with audio functionality.

W

• WAN (Wide Area Network)
  A network that covers a broad area. Cellular networks are a type of WAN used extensively in IoT.
• Wearables
  IoT devices worn on the body, such as smartwatches or health monitors, often connected via Bluetooth or LTE.

Z

• Zigbee
  A wireless mesh protocol often used in home automation, smart lighting, and building management systems.