M2M & IoT Glossary

The gateway settings that tell a SIM card how to connect to the mobile operator's network and from there to the internet (or a private network). IoT deployments often use a private APN to keep device traffic isolated from the public internet. APN settings include a name, username, password, and sometimes an IP type.

A one-off charge levied by some providers when a SIM is first provisioned and activated on the network. Many IoT-focused MVNOs offer free activation to reduce upfront deployment costs, particularly for large-volume customers.

The maximum rate at which data can be transferred over a cellular connection, measured in kilobits per second (kbps) or megabits per second (Mbps). For most IoT applications, bandwidth requirements are low — what matters more is latency and reliability.

An LTE standard designed for IoT devices that need moderate data speeds (10 Mbps download, 5 Mbps upload) with lower complexity than full 4G. Widely used for GPS trackers, alarm panels, and POS terminals. Supported on existing 4G infrastructure worldwide.

The geographic area in which a cellular network provides connectivity. IoT deployments should assess indoor coverage, building penetration, and rural coverage separately from outdoor coverage maps. Multi-IMSI SIMs can automatically switch networks to maximise coverage.

The maximum data allowance included in a SIM plan per billing period. Devices that exceed the cap may be throttled, charged overage rates, or disconnected depending on the provider. Data pooling plans share a single cap across all SIMs in a fleet.

A billing arrangement where multiple SIMs share a single data allowance. Heavy-usage devices draw more from the pool while light-usage devices use less, reducing waste compared to per-SIM fixed plans. Particularly cost-effective for fleets with variable usage patterns.

Using cellular data outside the home network's geographic coverage area, typically on a partner network. For IoT, roaming SIMs are common in global deployments — but roaming rates and reliability vary significantly. Unsteered roaming gives devices freedom to connect to the strongest available network.

A security and resilience architecture using two independent communication paths (e.g., cellular + broadband) for alarm and monitoring systems. Required by many insurers for Grade 3+ alarm installations. Cellular backup SIMs are commonly used as the secondary path.

A 3GPP power-saving feature for LTE-M and NB-IoT devices. Rather than continuously listening for network pages, the device wakes at configurable intervals (from seconds to hours), dramatically reducing power consumption. Works in conjunction with PSM for maximum battery life.

A programmable SIM that supports remote provisioning of operator profiles over-the-air (OTA). Devices with an eSIM can switch carriers without a physical SIM swap, making them ideal for global deployments or products that may change operator. Available in removable form or soldered MFF2 chip format.

Automatic switching to a backup network or connectivity method when the primary connection fails. Multi-IMSI SIMs can failover between operators automatically. Some deployments combine cellular primary with satellite or Wi-Fi backup for mission-critical applications.

The global industry organisation representing mobile network operators and the broader mobile ecosystem. The GSMA defines standards for eSIM (SGP.22, SGP.32), M2M connectivity, and IoT security. Their SGP.02 standard governs M2M eSIM remote provisioning.

A periodic 'keep-alive' message sent by an IoT device to confirm it is still online and functional. Heartbeats consume minimal data (often just a few bytes) but are critical for monitoring device health. Alarm panels typically send heartbeats every few minutes to a monitoring centre.

The unique 19–20 digit serial number printed on a SIM card, also encoded within it. Used to identify the SIM on a network and in management platforms. The ICCID is not the same as the phone number (MSISDN) or the subscriber identity (IMSI).

A 15-digit code that uniquely identifies a cellular device (modem, router, or phone), independent of the SIM. IMEI locking binds a SIM to a specific device — useful for preventing SIM theft in unattended deployments. The IMEI is separate from the SIM's own identifiers.

A unique identifier stored on a SIM card that identifies the subscriber on a mobile network. The IMSI is used internally by networks for authentication and routing — it is not the same as the phone number. Multi-IMSI SIMs store multiple IMSIs to connect to different operators.

A network of physical objects ('things') embedded with sensors, software, and connectivity that enables them to collect and exchange data. M2M SIM cards provide the cellular connectivity backbone for IoT deployments across sectors including fleet, utilities, healthcare, and industrial monitoring.

A category of wireless networks designed for long-range, low-power, low-bandwidth IoT communications. Cellular LPWAN standards include NB-IoT and LTE-M. Non-cellular LPWANs include LoRaWAN and Sigfox, but these require separate infrastructure and are not carried on M2M SIM cards.

Also known as Cat-M1 or eMTC. An LPWAN standard built on 4G LTE infrastructure, optimised for IoT devices. Supports mobility (handover between cells), voice, and data speeds up to ~1 Mbps. Excellent for mobile assets like GPS trackers and wearables. Uses PSM and eDRX for battery efficiency.

Direct communication between devices without human intervention. M2M SIM cards are specifically designed for devices rather than people — they're configured for always-on connectivity, remote management, and extreme durability. The terms M2M and IoT are often used interchangeably, though IoT is the broader modern term.

A chip-scale SIM (6×5mm) that is soldered directly onto a device's PCB rather than inserted into a slot. MFF2 SIMs withstand extreme temperatures (-40°C to +105°C), vibration, and shock — making them essential for automotive, industrial, and outdoor applications. They cannot be physically removed or swapped.

A lightweight publish/subscribe messaging protocol widely used in IoT applications. MQTT minimises data overhead (as little as 2-byte headers) making it ideal for low-bandwidth M2M devices. Runs over TCP/IP and typically uses TLS encryption for security. Common alternative is CoAP for very constrained devices.

The phone number associated with a SIM card. In IoT deployments, many SIMs are 'data-only' and have no MSISDN, or are assigned a private number used only for SMS-based management commands. Not to be confused with the IMSI (subscriber identity) or ICCID (card serial number).

A SIM technology where the card stores multiple operator profiles (IMSIs) and can automatically switch between them based on coverage, cost, or network availability. Provides built-in redundancy and is key to true multi-network SIM cards. Different from eSIM: Multi-IMSI profiles are pre-loaded at manufacture, not provisioned remotely.

A mobile operator that resells connectivity using another operator's network infrastructure under its own brand and commercial terms. Most specialist M2M/IoT SIM providers are MVNOs — they buy wholesale capacity from MNOs and package it with IoT-optimised features like management platforms, pooled data, and private APNs.

A 3GPP LPWAN standard optimised for stationary, low-data devices. NB-IoT operates in licensed spectrum using existing LTE infrastructure, offering deep indoor penetration and very long battery life (10+ years). Best for devices that rarely transmit small amounts of data: smart meters, bin sensors, soil monitors.

An open communication standard between electric vehicle charging stations and central management systems. OCPP messages include session start/stop, energy metering, payment processing, and firmware updates. EV charger SIM data requirements are driven largely by OCPP heartbeat and transaction message volume.

Remote delivery of software updates, configuration changes, or operator profile downloads to a device or SIM card without physical access. OTA firmware updates can fix bugs and add features without sending technicians to site. eSIM OTA provisioning (RSP) allows carrier profiles to be downloaded remotely.

A billing model where customers are charged only for the data they consume, with no monthly minimum or bundle. PAYG is ideal for low-usage devices (alarms, sensors) or irregular deployments. It offers maximum flexibility but typically has a higher per-MB rate than committed plans.

A dedicated network access point configured exclusively for a customer's devices, isolating their traffic from the public internet. Devices on a private APN communicate over a private IP range and cannot be directly reached from the internet — improving security. Typically paired with a VPN or MPLS link back to the customer's network.

A 3GPP feature that allows LTE-M and NB-IoT devices to enter a deep sleep state between transmissions, drawing near-zero current. The device negotiates a sleep period with the network (from seconds to hours). When active time arrives, it wakes, transmits, and sleeps again. Critical for achieving multi-year battery life.

A commercial contract between two mobile operators allowing each other's customers to use the network. The breadth and quality of a provider's roaming agreements directly determines how many countries their SIMs work in and at what quality. Some MVNOs have roaming agreements with 700+ networks across 190+ countries.

The GSMA-defined process for downloading, enabling, and deleting operator profiles on an eSIM over a secure connection. Consumer eSIM (SGP.22) is designed for end-user devices. M2M eSIM (SGP.02) is designed for machine devices managed remotely by a SM-DP server. RSP removes the need to ship pre-provisioned SIMs to devices in the field.

A small chip that authenticates a device on a cellular network. It stores the subscriber identity (IMSI), network authentication keys, and optionally applications. M2M SIM cards are hardened for industrial use — wider temperature ranges, longer operational life (10+ years), and remote management capabilities compared to consumer SIMs.

The physical size and format of a SIM card. Standard removable formats: 2FF (Mini, 25×15mm), 3FF (Micro, 15×12mm), 4FF (Nano, 12.3×8.8mm). Industrial formats: MFF2 (soldered chip, 6×5mm). Programmable: eSIM (built into the module or as MFF2). Choice depends on device size, environment, and whether field-swapping is needed.

A fixed, unchanging IP address assigned to a SIM card, allowing inbound connections to a device from a known address. Essential for CCTV cameras that need to be remotely viewed, modems that accept incoming connections, and any device acting as a server. Usually available as an add-on, often combined with a private APN.

A roaming configuration where the network steers a SIM to connect to a specific preferred partner operator when roaming, rather than the strongest available signal. Used by providers to control costs and ensure consistent quality on vetted networks. The opposite of unsteered roaming.

A roaming configuration where a SIM connects to whichever available network has the strongest signal, regardless of operator agreements. This maximises coverage and resilience but can result in variable quality and cost. Preferred for mission-critical applications where connectivity is paramount. Sometimes called 'true roaming'.

An encrypted tunnel that secures data in transit between a device and a central network or server. In IoT deployments, VPNs are commonly used with private APNs to create a secure end-to-end link from field devices back to a corporate network or cloud platform, preventing interception of sensitive data.

Successive generations of cellular network standards. 2G (GSM/GPRS) remains used in legacy M2M devices and areas with limited infrastructure. 3G is being sunset globally. 4G LTE is the dominant standard for IoT today, used with Cat-1, LTE-M, and NB-IoT variants. 5G introduces network slicing and ultra-low latency for next-generation industrial IoT.