Telecom Glossary of Terms

5G Standalone (SA) is a 5G network that runs on a native 5G core, independent of any 4G infrastructure. It enables the full set of 5G capabilities — such as network slicing, ultra-low latency and massive IoT — rather than relying on an existing LTE core.

Authentication Server Function (AUSF) is the 5G core function responsible for authenticating subscribers, working together with the UDM to secure access to the 5G network.

AAA refers to Authentication, Authorization, and Accounting. These three components play a crucial role in ensuring secure access to network services and managing billing and usage information. Choosing a robust and secure AAA solution is key so that broadband operators can deliver reliable network services to consumers.

The Integrated SIM (iSIM) is the next step in the evolution of the SIM card. An iSIM is embedded within a Tamper-resistant element (TRE) on the device’s system-on-a-chip (SoC) and is the most advanced, efficient and flexible device-side network equipment. It eliminates the need to depend on discrete SIM hardware and can be activated wirelessly using an industry-wide secure protocol. The iSIM is especially beneficial in the era of 5G, enabling low-power wide area (LPWA) networks for IoT devices of any form factor.

The Embedded SIM (eSIM) is an unremovable embedded SIM built into the phone’s board. It is rewritable and compatible with all leading carriers. eSIM specifications are standardised to allow interoperability and enable remote SIM provisioning of any mobile device. eSIM lets you switch providers with the touch of a button, and brings advantages to all stakeholders: simpler onboarding for end-users, simplified logistics for service providers, and new business opportunities for carriers across a wide range of connected devices.

The Equipment Identity Register (EIR) is a network entity used in GSM networks that stores lists of International Mobile Equipment Identity (IMEI) numbers, which correspond to physical handsets (not subscribers). The EIR can be used to reduce handset thefts by preventing stolen or disallowed handsets from accessing the network, using three lists:

• Blacklist — Mobile Stations denied access to the network.
• Greylist — Mobile Stations allowed on the network but tracked.
• Whitelist — Mobile Stations with full access to the network.

Fixed Wireless Access (FWA) delivers broadband to homes and businesses over the mobile network instead of fixed cabling, a common way for operators to provide connectivity in areas with limited fixed infrastructure.

A Full Core is a complete mobile core network combining all control-plane and subscriber-management functions — HLR/HSS, UDM, Policy, AAA, SMSC, IMS and 5G SA — in a single modular platform, deployable component by component or as a whole.

Home Location Register (HLR) is the centralized subscriber database used in 2G and 3G mobile networks, containing details of subscribers authorized to access the mobile operator’s network. This database stores phone number information, authentication data, and subscriber information such as service profiles and current location, using the SS7 MAP protocol. As mobile networks evolved to 4G and 5G, the HLR’s functionality was absorbed by the Home Subscriber Server (HSS) and, more recently, the Unified Data Management (UDM), which extend subscriber data management to LTE and 5G core network architectures.

Home Subscriber Server (HSS) is the evolution of the HLR for the 4G networks. Similar to the HLR, the main function of the HSS is to communicate with the network and provide subscriber profile and authentication information. The HSS stores information about subscribers to assist in authorization, device details, as well as user location and service information. It is based on Diameter protocol.

International Mobile Subscriber Identity (IMSI) is the unique identifier assigned to each mobile subscriber, stored on the SIM and used by the network to authenticate and manage the subscriber.

IP Multimedia Subsystem (IMS) is the architectural framework that delivers IP-based voice and multimedia services, such as VoLTE and VoWiFi, over mobile and fixed networks.

A Mobile Network Operator (MNO) is a provider of wireless communications services that has or manages the infrastructure necessary to sell and provide services to end users (subscribers), including the allocation of radio spectrum, wireless network infrastructure, transportation infrastructure, billing, customer service and provisioning of computer systems, repairs, and more.

Mobile Station ISDN Number (MSISDN) is the full phone number associated with a mobile subscription, used to route calls and messages to the subscriber.

A Mobile Virtual Network Aggregator (MVNA) can incorporate many small MVNOs and, using their collective power, connect to the operator as a single MVNO. The MVNA usually does not have direct subscribers of its own, but connects smaller MVNOs. In general, you would need to have your own OSS/BSS in order to provide accurate billing information to MVNOs.

A Mobile Virtual Network Enabler (MVNE) is a company that supplies the necessary network infrastructure, as well as services, business support, administration and operations support to a Mobile Virtual Network Operator (MVNO). MVNE allows MVNOs to offer services to their own clients with their own brands. An MVNE does not manage a relationship with consumers directly — it is a provider of network enablement platforms and services. MVNEs carry out the planning, implementation and management of mobile services, including SIM provisioning and configuration, customer billing, customer relationship management, and value-added service platforms.

A Mobile Virtual Network Operator (MVNO) is a provider of wireless communications services that does not own the wireless network infrastructure through which it provides services to its customers. An MVNO needs a mobile network operator to gain access to network services at wholesale prices, then can independently set retail prices as well as use its own customer service, billing support systems, marketing and sales staff — or use the services of a Mobile Virtual Network Enabler (MVNE).

Network Slicing is a 5G capability that partitions a single physical network into multiple isolated virtual networks (slices), each tuned to a specific use case — for example, low latency for industry or high throughput for consumers.

Non-Terrestrial Networks (NTN) extend mobile connectivity through satellites and other airborne platforms, providing coverage where terrestrial networks cannot reach, integrated with the mobile core through 3GPP standards.

PCRF (Policy and Charging Rules Function) serves as the cornerstone of policy and charging management. Its primary function lies in establishing and enforcing policies related to network resource allocation, quality of service, and access control. By defining rules and conditions for various services — such as data prioritisation and bandwidth allocation — PCRF empowers service providers to offer tailored experiences to their subscribers.

PCF (Policy Control Function) handles policy control in 5G networks, enabling service providers to manage network access, security, and data traffic. By integrating PCF with other network elements, policy rules can be enforced at the network edge, ensuring effective traffic management, optimal bandwidth utilisation and improved network security.

Policy Control Function (PCF) is the 5G core function that manages network policy — quality of service, charging rules and access control. It is the 5G evolution of the PCRF.

A private LTE network is a local cellular network that has cell sites and core network servers dedicated to supporting the connectivity of a particular organisation’s requirements, independent of the cellular networks of service providers. Private LTE networks are important for organisations that use multiple devices and applications. Combined with 4G and 5G technology, they supply a stability of service that outstrips wireless connectivity. Dedicated to and managed by the organisation itself, they’re designed for high-speed mobility and secure mobile roaming within an organisation’s business premises and land.

Reduced Capability (RedCap) is a 5G device category for mid-tier IoT — such as sensors, wearables and cameras — that need more than low-power IoT but less than full 5G, balancing performance, cost and battery life.

Roaming allows a subscriber on one mobile network to access services in another region from a different service provider or operator. The most common example is accessing the services of a provider in another country outside the subscriber’s home country.

Short Message Service Center (SMSC) is the network element that routes, stores and forwards SMS messages between subscribers, including person-to-person messaging and IoT/M2M signalling.

Subscriber Data Management (SDM) is the layer of the mobile core responsible for centralising subscriber profile data across 2G, 3G, 4G and 5G networks in a single logical data store. The SDM typically covers the functions of the HLR, HSS, and in 5G SA deployments, the UDM, UDR and AUSF — enabling unified subscriber identity management regardless of the access network generation.

Unified Data Management (UDM) is the 5G core function that stores and manages subscriber data and identities. It is the 5G evolution of the HSS, providing authentication, authorization and subscription information in a Standalone 5G network.

Unified Data Repository (UDR) is the 5G core function that stores subscription, policy and application data in a single repository, accessed by functions such as the UDM and PCF.

The Visitor Location Register (VLR) has information about roaming mobile stations in one or more MSC areas. A VLR contains information on all active subscribers in that area, including your home network. Generally, most of the registry entries are not visitors, but users on your own home network.

Voice over Internet Protocol (VoIP) is defined as a set of standards for the transmission of multimedia data and voice content using the Internet Protocol (IP). The voice signal is sent in the form of digital data packets rather than in analog form. The use of VoIP allows lower costs, greater functionality and integration with other applications, though it depends on the bandwidth available on the network.

Voice Over Long Term Evolution (VoLTE). This technology helps users to simultaneously send voice and data over the network without losing voice quality. The voice quality is high and the user can keep the data connection on while making a voice call. Another advantage is it allows connecting calls faster.

Voice over New Radio (VoNR) is voice service carried natively over a 5G Standalone network, without falling back to 4G. It is the 5G equivalent of VoLTE, delivering voice directly over the 5G core and radio.

Voice over WiFi (VoWiFi): Along with IMS technology, it provides a voice packet service over IP in a WiFi network, so it is not necessary to have a mobile signal to make and receive calls. Another advantage is that it enables existing SIM-based security and authentication for VoLTE.