Glossary

The 5G core control-plane function that terminates device signalling: registration, authentication, connection and mobility management. It hands session handling to the SMF. The AMF takes over the MME's role in standalone (SA) 5G, but session management moved out of it into the SMF.

An SBC deployed at the edge between subscriber access networks (mobile, fixed, Wi-Fi, enterprise SIP trunks) and the IMS core. It usually hosts the P-CSCF function, protects the core from untrusted devices, handles NAT traversal, and anchors media where required.

A billing or service entity that groups one or more subscriptions under a single customer relationship. Accounts hold financial responsibility and are the anchor for invoicing, payments, and credit management.

The process of making a service or resource operationally live on the network. Activation translates logical service parameters into device-level configuration commands sent to network elements.

A design pattern that introduces a translation boundary between two systems or bounded contexts with different domain models. In telco, it prevents legacy system data models from leaking into modern catalog-driven services.

A single entry point that routes, authenticates, and rate-limits all inbound API traffic before it reaches backend microservices. In ODA deployments, the API gateway maps external consumers to internal TMF Open API endpoints.

Ordering a change against the product instance the customer already has — modify, add to, cease — rather than selling it as new. It lets the network change only what changed and billing prorate from the right date. It fails for customers whose products have no instance to point at.

The eTOM process area responsible for monitoring, diagnosing, and resolving issues with services and resources. Assurance encompasses fault management, performance management, and SLA compliance tracking.

Business-to-Business: the commercial model where a telecom operator sells services to enterprise customers rather than individual consumers. B2B ordering involves complex quoting, multi-site fulfilment, SLA-backed contracts, and partner/wholesale relationships.

Business-to-Consumer: the commercial model where a telecom operator sells services directly to individual end-users. B2C flows prioritise self-service, fast fulfilment, and simple product bundles.

An architectural pattern where a dedicated backend service is built for each frontend channel (web portal, mobile app, agent desktop). Each BFF aggregates and shapes data from multiple downstream APIs to match its channel's specific needs.

The BSS function that generates invoices based on rated usage events and recurring charges. Billing aggregates charges at the account level, applies discounts and taxes, and produces customer-facing bills.

The account that pays: payment method, bill cycle, balance and bill address. One customer can have several, and the products on one billing account can be used by people who are not the customer. Usually held in billing, shown in CRM.

In Nokia IMS deployments, the element that carries the IMS border control functions. In vendor-neutral 3GPP terms these are the P-CSCF and IMS Access Gateway at the access edge, and the IBCF and Transition Gateway at the interconnect edge: the roles usually described as an Access SBC and an Interconnect SBC. As with any border element, it is also a point where voice traffic can be intercepted and interconnect usage recorded.

The suite of systems managing the commercial side of a telecom operator: customer relationships, product catalogs, orders, billing, and revenue. BSS is the source of truth for what the customer bought and what they owe.

The SIP session control layer of IMS, split into three roles: the Proxy-CSCF (first contact point for the device), the Interrogating-CSCF (entry point from other networks, finds the right S-CSCF) and the Serving-CSCF (registers the user and triggers application servers). It routes sessions; the call features themselves are provided by the application servers it invokes.

The Concept-to-Market function that turns an approved product concept into governed, versioned, published catalog entities — the commercial layer (Product Offering, Product Specification, ProductOfferingPrice under TMF620) and the service and resource layers (Customer-Facing Service and Resource-Facing Service under TMF633, both being service specifications; Resource Specification under TMF634). It owns the reuse decision, versioning and effective dating, and the gates a specification passes before publication.

A design philosophy where product, service, and resource catalogs are the single source of truth for what can be sold, delivered, and managed. All downstream systems (ordering, fulfilment, billing) derive their behaviour from catalog definitions rather than hard-coded logic.

Nokia's IMS SIP session control product, providing the Proxy-, Interrogating- and Serving-CSCF functions. It is IMS, not 5G core, although it serves VoNR over the 5G core. "CFX LI" refers to lawful interception of the IMS sessions it controls, which is part of the operator's wider LI solution rather than a separate network function.

The real-time or near-real-time process of rating usage events (e.g. voice minutes, data consumption) against a pricing plan and applying charges to a customer's balance. Distinct from billing, which aggregates charges into invoices.

Nokia's packet core gateway product. A single software platform delivers the user- and control-plane gateway functions across generations: GGSN (2G/3G), SGW/PGW (4G), and SMF/UPF (5G). It commonly also includes functions such as DPI. On the vendor-neutral view it is an implementation of those 3GPP functions, not a function in its own right.

Nokia's mobility management product, a control-plane platform that provides the SGSN (2G/3G), MME (4G) and AMF (5G) functions on one software base. Running all three on one platform lets 4G and 5G mobility management coexist while standalone 5G is phased in.

A network function implemented as containerised microservices running on Kubernetes or a similar container orchestration platform. CNFs are the cloud-native evolution of VNFs, designed for horizontal scaling and rolling upgrades.

The BSS capability that captures, validates, and manages customer-facing orders. COM decomposes a commercial order into the product actions required, then delegates technical fulfilment to SOM. It is the source of record for order intent.

The design-time process that defines, models, governs, and publishes what can be sold, turning a commercial idea into catalog entities that runtime systems can execute against. It runs through the Product Portfolio Function, the Catalog Governance Function, and the Implementation Function. C2M ends at catalog publication; Lead-to-Cash begins at the first order taken against a published offer.

The practice of holding intended network configuration in a version-controlled repository and deploying it through reviewed, automated pipelines (often called GitOps when git is the trigger). The repository, not the device, is the source of truth for what the configuration should be. It lives in the automation layer below ROM.

An individual person associated with a customer or account. Contacts hold communication preferences, roles, and authorisation levels (e.g. billing contact, technical contact, authorised signatory).

The governance of a contract as a living object, from the moment a quote is accepted until the contract terminates: creation, in-life obligations and entitlements, mid-term amendments, renewal, and termination. CPQ produces the deal; CLM governs it afterwards. The distinction matters because a quote is a point-in-time artifact that stops changing on acceptance, while a contract keeps changing for years — a system built on the assumption that the quote is final cannot represent an amendment eighteen months into a three-year term. CLM owns obligation and entitlement truth; it does not provision service, hold the running subscription, or measure usage.

The BSS capability that turns catalog content and customer intent into a priced, approvable, fulfillable quote. Configuration assembles a valid solution against catalog rules (mandatory components, compatibility, dependencies); pricing applies list price, discounts, and any negotiated override; quoting produces the formal offer that is versioned, approved, and accepted. CPQ owns the quote — not product truth (the catalog), customer truth (CRM), or billing truth (rating and invoicing), and its job ends at the accepted quote: fulfilment is a COM/SOM/ROM concern. It does not fix a badly modelled catalog; it will faithfully configure an inconsistent product.

Command Query Responsibility Segregation: a pattern that separates read and write models into distinct paths. In telco, CQRS is often used in inventory systems where high-throughput order writes and complex search queries have very different performance profiles.

An assessment of whether a customer is likely to pay, made before the operator carries risk — postpaid plans, handset instalments. The operator’s own rules turn credit-bureau data into a decision that is rarely yes or no: approve, approve with a deposit or limit, offer prepaid instead, or decline.

Customer Relationship Management: the BSS system that manages customer identities, interactions, and engagement history. CRM is typically the system of record for customer and account master data.

A party (individual or organisation) that has a commercial relationship with the operator. The customer entity is the root of the BSS data model and links to accounts, subscriptions, orders, and trouble tickets.

A service defined from the customer's perspective (e.g. "Broadband 100 Mbps", "Mobile Voice"). A CFS maps to one or more Resource-Facing Services and is the bridge between what the customer buys (product) and what the network delivers.

Day-0 covers initial planning and design of a network function. Day-1 covers deployment, instantiation, and initial configuration. Day-2 covers ongoing lifecycle management including scaling, healing, monitoring, and upgrades.

Inspection of traffic beyond the packet headers to identify the application or service in use. In the mobile packet core, DPI (usually built into the gateway or UPF) is what lets an operator zero-rate an app, throttle a traffic class or report usage per service. Encryption keeps reducing what DPI can reliably identify, and traffic-management uses of it are constrained by net neutrality rules in many markets.

An order that expresses only the differences (additions, removals, changes) relative to the current state of a subscription, rather than restating the entire subscription. Delta ordering simplifies MACD flows but requires robust baseline tracking in product inventory.

A model of the live network maintained alongside it, used for what-if analysis — testing a change, a failure or a capacity scenario before it is applied for real. A design-time aid in the automation layer, and a runtime one only if it is kept continuously in sync with the real network — its value depends entirely on that.

A pricing adjustment that reduces the standard price of a product offering. Discounts can be percentage-based, fixed-amount, or volume-tiered, and are typically managed in the product catalog alongside price rules.

BSS capabilities specifically tailored for B2B and enterprise customers, including complex quoting (CPQ), hierarchical account structures, SLA-driven pricing, multi-site ordering, and partner/wholesale management.

The enhanced Telecom Operations Map, TM Forum's process framework that defines the full set of business processes a telecom operator needs. eTOM is organised in levels (L0-L4) across Strategy, Operations, and Enterprise Management domains.

An asynchronous message published when a state change occurs in a system (e.g. order status changed, inventory item created). TMF Open APIs define standard notification payloads using a publish/subscribe or webhook model.

An architectural style where systems communicate by producing and consuming asynchronous events rather than synchronous request/response calls. In telco, event-driven patterns decouple order management, inventory, and activation systems.

The 4G EPC gateway that lets devices reach the packet core over untrusted non-3GPP access, typically public or home Wi-Fi. The device builds an IPsec tunnel to the ePDG, which then connects it to the PGW. It is the network element behind Voice over Wi-Fi (VoWiFi) calling.

The OSS discipline responsible for detecting, isolating, and correcting faults in network resources and services. Fault management processes alarms, correlates events, and drives trouble ticket creation.

The end-to-end eTOM process area covering everything from order capture to service activation. Fulfilment spans COM, SOM, and ROM and ensures the customer receives what they ordered.

The 2G/3G packet core gateway that anchors a subscriber's data session and connects it to external packet networks (the internet or an enterprise APN). It allocates the device IP address and generates charging records for the session. In 4G its role passed to the PGW; many operators still run GGSN function on the same converged gateway for legacy devices.

The gRPC Network Management Interface — a protocol for configuring devices and, more importantly, streaming telemetry from them, so state is pushed continuously rather than polled. Usually paired with the vendor-neutral OpenConfig data models. Part of the interface layer below ROM.

Rule-driven configuration that walks a seller or self-service customer to a valid, deliverable solution instead of relying on the seller to know the product model. The rules encode catalog reality — mandatory components, compatibility and dependency constraints, eligibility, end-of-sale dates — alongside commercial constraints such as discount thresholds and geographic restrictions. Guided selling is a consumer of catalog governance, not a substitute for it: the wizard can only be as correct as the offering and specification model beneath it, and encoding the rules in the configurator rather than the catalog is how the two silently diverge.

Everything each customer currently has, as product instances in product inventory, each linked to the offering it was sold from, the account that pays and the services that deliver it. Every in-life change depends on it being right.

An automation approach in which the operator declares the outcome required — reachability, bandwidth, isolation — and a controller derives, applies and continuously maintains the device configuration that delivers it. The controller owns the translation from intent to configuration; ROM supplies the intent in TMF resource terms.

An SBC deployed at the edge between the operator's IMS core and other operators' networks (IP interconnect, roaming, IPX). It performs topology hiding, SIP normalisation between network implementations, codec transcoding and interconnect policy. Its call records are also a source for interconnect settlement, which links it directly to wholesale billing.

The 3GPP SIP-based core for voice, video and messaging over IP: VoLTE, VoNR, VoWiFi and fixed VoIP. Its main elements are the session control (CSCF), application servers (TAS), border control (SBC), media (MRF) and interworking with circuit-switched networks (MGCF/MGW). With 2G/3G shutdowns, IMS becomes the only voice path, so its readiness (including emergency calling and roaming) sets how fast legacy networks can be switched off.

The discipline that governs technology assets, their cost, contracts, licence compliance and lifecycle from request to disposal. In a telco the largest asset base is network equipment and CPE, and one device is an asset (asset register), a configuration item (CMDB) and a resource (resource inventory) at once. An ITIL 4 practice with ISO/IEC 19770 as its standard; eTOM places it in Enterprise Management, not Assurance.

The discipline that keeps the technology estate visible, healthy and available: discovery and dependency mapping, event and alarm management, performance monitoring, correlation and automated remediation. In a telco it is split between ITOM tools for the IT estate and OSS fault and performance management for the network. One of the three pillars of service assurance; an IT-industry term, not a TM Forum one.

The discipline that manages how technology services are supported for the people who use them: incident, problem, request, change and service level management. In a telco it runs customer-facing Trouble-to-Resolve, owns the ticket and the SLA clock, and its platform usually holds the CMDB. One of the three pillars of service assurance, with ITOM and ITAM; an IT-industry term (ITIL), not a TM Forum one.

Know Your Customer: verifying that a person is who they say they are. In telecoms it is often a legal duty before a SIM is activated (SIM registration), prepaid included, and it is repeated at fraud-prone moments such as a SIM swap. TM Forum has no dedicated KYC API; the verification is an integration with a specialist service.

The legally mandated capability to deliver a target subscriber's communications and related data to an authorised law enforcement agency. Interception points exist in both the packet core (gateways, SMF/UPF) and the IMS voice core (CSCF, TAS, SBC), feeding a mediation function that hands data to the agency over standardised interfaces (ETSI / 3GPP). It is a licence condition, not an optional feature: a new core, voice platform or MVNO host arrangement cannot go live until LI is in place and accepted.

A sign that someone might buy — an enquiry, a register-interest form, an abandoned basket, a customer near the end of their contract — captured before any order exists. A lead is not yet a customer; it is recorded once, with the consent given, and linked to the person if they already are one.

The eTOM end-to-end business flow from initial customer engagement through to revenue collection. It encompasses marketing, selling, ordering, fulfilment, billing, and payment across BSS and OSS systems.

Move, Add, Change, Disconnect: the four fundamental lifecycle operations on an existing subscription. MACD orders modify the product inventory baseline and trigger downstream service and resource changes.

Management and Orchestration: the ETSI NFV framework for lifecycle management of virtualised network functions. MANO comprises three functional blocks: NFVO (orchestrator), VNFM (VNF manager), and VIM (virtualised infrastructure manager).

The element that converts media between circuit-switched (TDM) and packet (IP) networks, under the control of an MSC Server or an IMS MGCF. It is what lets IMS calls reach the legacy PSTN and 2G/3G circuit-switched networks. Its traffic falls as TDM interconnect is retired, but it stays in service as long as any TDM partner or legacy access remains.

The IMS element that provides media processing: announcements, tones, conference bridging, transcoding and media recording. It is split into a controller (MRFC) and a media processor (MRFP), and is invoked by application servers such as the TAS.

An architectural style where an application is structured as a collection of small, independently deployable services, each owning its own data and communicating via APIs or events. Microservices are the target architecture for ODA components.

The 4G EPC control-plane node that handles device attach, authentication (with the HSS), tracking and paging, and bearer setup by selecting the SGW/PGW. It is the 4G predecessor of the AMF. In 5G non-standalone (NSA) deployments the MME remains in service, because the 4G core still controls the device.

An application server platform of Alcatel-Lucent heritage (now Nokia) that hosts service applications across IMS, legacy Intelligent Network (IN) and hybrid networks. It connects over SIP and Diameter (IMS), HTTP, SMS and SS7. It is typically found where operators still run IN-era services (prepaid, VPN, number translation) alongside IMS.

A software architecture where all functionality is deployed as a single, tightly coupled unit. Many legacy BSS/OSS platforms are monolithic, making them difficult to scale, extend, and integrate independently.

The call control part of a split-architecture mobile switching centre for 2G/3G circuit-switched voice (also called a Mobile Softswitch). It handles call control and mobility while one or more Media Gateways carry the media. It also supports interworking with 4G voice (for example SRVCC handover from VoLTE to 2G/3G). Vendors ship it in different hardware and virtualised deployment variants, which some operators label with prefixes such as vMSS; the function is the same. It is retired with 2G/3G, once no voice, roaming or emergency traffic still depends on it.

The ability to place a single B2B order that provisions services across multiple geographic locations for an enterprise customer. Multi-site orders require coordination of site surveys, access availability, and per-site fulfilment timelines.

Mobile Virtual Network Operator: a company that provides mobile services to end-users without owning radio network infrastructure, instead leasing capacity from a host MNO. MVNOs require BSS capabilities for retail operations and wholesale settlement with the host.

The IETF network configuration protocol (RFC 6241): a transactional way to read and write device configuration expressed in YANG data models, with validation, commit and rollback. The workhorse of model-driven automation. RESTCONF (RFC 8040) exposes the same YANG models over HTTP. Both sit in the interface layer below ROM.

A physical or virtual device in the network (e.g. router, switch, OLT, base station) that is individually managed and appears in the resource inventory. Network elements are the lowest level of the resource domain hierarchy.

The totality of hardware and software components that form the environment in which VNFs are deployed. NFVI includes compute, storage, and networking resources managed by the VIM layer of MANO.

The 5G core registry that network functions register with and query to discover each other in the service-based architecture (SBA). An AMF finds an SMF, or an SMF finds a UPF, by asking the NRF. When the NRF is unavailable or holds wrong data, the other network functions cannot find each other, which is why it is deployed with high redundancy.

Nokia's 5G core product that provides the NRF and NSSF functions: network function registration and discovery, plus network slice selection, for the service-based architecture.

A service orchestration platform (notably Cisco NSO) that automates network service delivery by abstracting device-level configuration into service models, pushing the result to devices via YANG/NETCONF. It sits in the automation layer below ROM, but the boundary is a deployment choice: NSO can be the executor that ROM calls, or be wrapped so that it is the ROM for a domain. What must stay fixed is that ROM owns the resource order and Resource Inventory holds the assigned state.

The 5G core function that selects which network slice instance(s) serve a device and which AMF set should handle it, based on the slices the device requests and is allowed to use. It applies slice decisions at runtime; it does not design slices. The slice definition still comes from the service catalog and orchestration layers.

The MANO component responsible for orchestrating the lifecycle of network services and coordinating VNF instantiation across the infrastructure. NFVO manages network service descriptors and delegates VNF-level operations to the VNFM.

The 5G core equivalent of the ePDG: it terminates IPsec tunnels from devices on untrusted non-3GPP access (such as Wi-Fi) and connects them to the AMF for signalling and the UPF for traffic, so the device is managed by the 5G core as if it were on 5G radio.

The runtime execution environment defined by TM Forum's ODA that hosts ODA Components. The Canvas provides common infrastructure services such as identity management, API exposure, event handling, and observability so that components can focus on business logic.

A self-contained, independently deployable software unit that implements a specific business capability within TM Forum's ODA. Each component exposes and consumes TMF Open APIs and declares its functional scope via a Component Descriptor.

A standardised REST API specification published by TM Forum that enables interoperability between BSS/OSS components. Each Open API covers a specific domain (catalog, ordering, inventory, etc.) with well-defined resources, operations, and notification events.

TM Forum's reference architecture blueprint for modular, cloud-native telecom IT systems. ODA defines standardised components, APIs, and a runtime canvas that together replace monolithic BSS/OSS stacks with interoperable, vendor-neutral building blocks.

The suite of systems managing the technical and network side of a telecom operator: service design, fulfilment, inventory, activation, assurance, and network management. OSS is the source of truth for what is running on the network.

The sub-process within fulfilment that covers the journey from a validated order to a live, activated service. It spans commercial order decomposition (COM), service orchestration (SOM), and resource provisioning (ROM).

A verification technique, not a migration strategy: both platforms process the same inputs over the same period — for billing, the same usage through the same bill cycles — and the outputs are reconciled while legacy remains the system of record. It is used before a cutover inside any migration pattern. It is not the same as two stacks coexisting with different customers on each.

The BSS capability for managing commercial relationships with third-party partners, including MVNOs, resellers, content providers, and wholesale carriers. It covers partner onboarding, agreement management, settlement, and revenue sharing.

A person (Individual) or an organisation (Organization) known to the operator, with its identification and contact details. A party exists independently of what it buys and can play several roles at once: customer, contact, user of a line.

A role a party plays in relation to the operator — Customer is one, as are contact, user and partner. Modelling customer as a role rather than a kind of person lets the same individual pay for one line, use another and be a contact on a third without duplicate records.

The 4G EPC gateway that connects the device to an external packet data network (PDN): it allocates the IP address, enforces policy and QoS rules received from the PCRF, and produces the usage records that feed online and offline charging. Where the PGW sits and which APNs it serves are what enterprise and MVNO data products are ultimately built on.

The OSS discipline focused on collecting, analysing, and reporting on network and service performance metrics (throughput, latency, error rates). Performance data feeds into assurance processes and SLA compliance monitoring.

A network function implemented on dedicated, purpose-built hardware (e.g. a physical router or firewall appliance). PNFs are managed alongside VNFs and CNFs in hybrid environments but are not orchestrated by MANO's VIM/VNFM.

The moment after which an order can no longer simply be amended or cancelled, typically when network work starts or a device ships. Commercial order management decides it; before it the order is changed, after it undoing the order takes a new order.

A monetary value or pricing structure attached to a product offering. Prices can be one-time, recurring, or usage-based and are defined in the product catalog. Pricing rules determine how base prices are modified by discounts, promotions, and contract terms.

The BSS repository that defines all sellable products (product offerings) and their specifications, pricing, eligibility rules, and relationships. The product catalog is the commercial source of truth in a catalog-driven architecture.

The BSS repository that records what each customer has actually purchased and currently holds (active subscriptions, installed products). Product inventory is the runtime counterpart of the product catalog and the source of record for the customer's installed base.

A marketable, sellable entity in the product catalog that combines a product specification with commercial terms (pricing, eligibility, promotions, channels). A product offering is what a customer sees and buys.

The Concept-to-Market function that decides what to build and in what order: intake from market, customer, internal, and regulatory sources; discovery and prioritisation against value, effort, and strategic fit; and a rolling roadmap. It owns the commercial intent, not the model — it models nothing. Its deliverable is an approved product concept decomposed far enough that the Catalog Governance Function can begin.

A technical blueprint that defines the structure, characteristics, and valid values of a product, independent of commercial terms. Multiple product offerings can reference the same specification, enabling catalog reuse.

The process of allocating and configuring resources (ports, IP addresses, VLANs, network functions) to support a service. Provisioning is the resource-level counterpart of activation and is typically handled by ROM or a resource activation system.

A formal proposal presented to a customer that details the products, prices, terms, and conditions of a potential order. Quotes are generated by CPQ, may undergo approval workflows, and convert into orders upon customer acceptance.

The eTOM process flow that handles customer-initiated modifications to existing services or subscriptions. It covers change requests, impact assessment, approval, and fulfilment of modifications (adds, changes, moves).

The OSS repository that defines all available resource types (physical devices, virtual functions, logical resources) and their specifications. The resource catalog drives what can be provisioned on the network.

The OSS repository that records the current state of all network resources: physical devices, virtual functions, logical resources, ports, and links. It is the source of truth for what exists on the network.

The OSS capability that receives resource-level orders from SOM and orchestrates the allocation, configuration, and activation of physical and virtual resources. ROM is the lowest orchestration layer before direct device interaction.

A definition in the resource catalog that describes the type, characteristics, and capabilities of a resource (e.g. a specific router model, a virtual firewall template, a VLAN). Resource specifications are referenced by RFS definitions.

A service defined from the network/resource perspective that represents a technical capability delivered by one or more resources. An RFS bridges the gap between the customer-facing service (CFS) and the physical or virtual resources that provide it.

Representational State Transfer: the architectural style underpinning all TMF Open APIs. RESTful APIs use standard HTTP methods (GET, POST, PATCH, DELETE) on resource-oriented URLs, with JSON payloads and standardised error handling.

The end-to-end BSS domain covering charging, billing, collections, and revenue assurance. Revenue management ensures that all services consumed are accurately rated, billed, collected, and reconciled.

A commercial arrangement where revenue from jointly delivered services is split between partners according to agreed terms. Revenue sharing requires settlement engines that can calculate, reconcile, and report partner shares.

A distributed transaction pattern that manages data consistency across multiple microservices using a sequence of local transactions with compensating actions. In telco ordering, sagas coordinate COM, SOM, and ROM steps with rollback capabilities.

A software-defined networking controller (OpenDaylight- and ONOS-class, and the vendor equivalents) that holds a centralised view of a network domain and programs its forwarding and configuration through southbound interfaces such as NETCONF, gNMI or OpenFlow. It sits in the automation layer below ROM: ROM expresses the resource change in TMF terms; the controller turns it into device state for its domain.

A place in a system where behaviour can be changed, substituted or intercepted without editing the code at that place — a boundary you can cut along. The term comes from Michael Feathers' Working Effectively with Legacy Code, where a seam is what lets legacy code be put under test by swapping a dependency. In BSS/OSS architecture it has broadened to mean any deliberate boundary that makes the estate separable: the catalog contract between product specification and CFS/RFS decomposition, a TMF Open API at a domain boundary, an anti-corruption layer between legacy and target, a strangler façade, an event bus. A monolith has no seams, which is why it cannot be migrated a piece at a time; a platform that claims to be composable should be able to show its seams and prove each one holds with a test.

The OSS repository that defines all available service types (CFS and RFS specifications) and their decomposition rules. The service catalog bridges product catalog entries to resource-level implementations.

The OSS repository that records all active service instances and their current state. Service Inventory tracks which CFS and RFS instances are running, their parameters, and their relationships to product and resource instances. Not to be confused with Subscription Lifecycle Management (SLM), which is the product-instance view underpinned by Product Inventory (TMF637).

A contractual commitment specifying measurable service quality targets (uptime, latency, response time) and the remedies or penalties if those targets are not met. SLAs are central to B2B and enterprise service delivery.

The OSS capability that receives service-level orders from COM and orchestrates their decomposition into resource-level tasks. SOM translates product actions into CFS/RFS operations and coordinates with ROM for resource provisioning.

Whether the network can deliver a service at an address — which technologies reach it and at what speed. A question about the address and the network, answered by OSS inventory; distinct from eligibility, which is about the person and the offer.

The 4G EPC user-plane node that routes a subscriber's data between the radio network and the PGW and acts as the mobility anchor when the device moves between cells. The SGW and PGW are frequently deployed together (S/PGW) on the same gateway platform; with control/user plane separation (CUPS) each splits into a control part and a user-plane part.

The 2G/3G packet core node that handles mobility management, authentication and session routing for data subscribers attached through the 2G/3G radio network, forwarding traffic to the GGSN. It is the 2G/3G predecessor of the MME; 2G/3G shutdowns retire it, but only once roaming, IoT and fallback traffic that still depends on it has been moved.

The network edge element for SIP signalling and media. It provides security (topology hiding, firewalling, DoS protection), NAT traversal, protocol interworking and transcoding, and admission control. It is deployed in two distinct positions with different jobs: the access edge (A-SBC, toward subscribers) and the interconnect edge (I-SBC, toward other networks).

The 5G core control-plane function that sets up, modifies and releases PDU sessions: it allocates the IP address, selects and programmes the UPF, and applies policy from the PCF. It takes over the control-plane half of the 4G SGW/PGW. For BSS/OSS, the SMF is where data network (DNN), slice and QoS choices made in the product and service catalogs finally become per-session behaviour.

A transient BSS entity that holds a customer's selected product offerings before order submission. The shopping cart enforces catalog rules, calculates prices, and converts into a formal order upon checkout.

Shared Information/Data Model: TM Forum's canonical data model that defines the entities, attributes, and relationships used across BSS and OSS. SID provides a common vocabulary so that different systems can exchange data unambiguously.

The Simple Network Management Protocol — the long-standing, polling-based protocol for reading device state and receiving traps. Rarely used for configuration — NETCONF took that role and gNMI the telemetry role — but still present on almost every element an operator owns. Any realistic interface layer must accommodate it.

The authoritative system that owns and masters a given piece of data. All other systems consuming that data must defer to the SoR. For example, CRM is typically the SoR for customer data, while product inventory is the SoR for installed products.

A migration pattern (named by Martin Fowler) that gradually replaces a legacy system behind a routing or interception layer — an API facade, order router or event interceptor. Capabilities, or slices of traffic, move to the new implementation one at a time and the router is re-pointed as each is proven, until nothing routes to legacy and it is retired. Sending only new customers or new products to a new stack while the existing base stays on legacy is customer-segmented or product-by-product migration, not strangler. Named after the strangler fig tree that slowly envelops its host.

The BSS capability that manages the end-to-end lifecycle of a customer's subscriptions: from initial activation through modifications (MACD) to eventual termination. It maintains the product inventory baseline.

A system optimised for user interaction and experience rather than data mastery. SoE systems (e.g. self-service portals, agent desktops) consume data from the SoR and provide rich UX, but do not own the authoritative copy of the data.

A system that provides read-only, aggregated, or derived views of data sourced from one or more SoRs. Reporting platforms, data warehouses, and analytics tools are typical systems of reference.

A packet core function that adjusts TCP behaviour on the radio side of a connection (congestion control, window sizing, buffering) to improve throughput over variable mobile links. Its benefit has shrunk as traffic has moved to encrypted and UDP-based transports such as QUIC, which it cannot act on in the same way.

The IMS application server that provides the telephony service logic: supplementary services such as call forwarding, barring, hold, conference and caller ID for VoLTE, VoNR, VoWiFi and fixed voice. NTAS is the common shorthand for Nokia's Telecom Application Server. What a voice product "includes" commercially is largely a set of TAS service settings per subscriber.

A global industry association that produces standards, frameworks, and best practices for the telecommunications industry, including eTOM, SID, ODA, and the TMF Open API suite.

The standardised notification mechanism defined by TM Forum for asynchronous communication between components. It uses a hub/listener model where consumers register for specific event types and receive callbacks when state changes occur.

The TMF Open API for managing the product catalog, including product offerings, product specifications, categories, and their relationships. TMF620 is the foundation API for any catalog-driven BSS.

The TMF Open API for creating, updating, and tracking trouble tickets. It supports the full lifecycle of issue management, from initial report through diagnosis, resolution, and closure.

The TMF Open API for managing product orders throughout their lifecycle. TMF622 defines the structure for order items, order actions (add, modify, delete), and order state transitions from acknowledged to completed.

The TMF Open API for managing service level agreements, including SLA templates, SLA instances, and SLA violation tracking. It supports the contractual assurance process for enterprise services.

The TMF Open API for the customer role: creating, reading and updating customers and their characteristics. It sits on top of the party (TMF632), because in TM Forum’s model a customer is a role a party plays.

The TMF Open API for managing individuals and organisations (parties). TMF632 covers party creation, role assignment, and contact management, serving as the foundation for customer and partner data.

The TMF Open API for managing the service catalog, including service specifications (CFS and RFS), service categories, and candidate relationships. TMF633 defines the service design-time model.

The TMF Open API for managing the resource catalog, including resource specifications, categories, and candidate relationships. TMF634 defines the resource design-time model for physical, logical, and virtual resources.

The TMF Open API for managing the product inventory, which holds all active and historical product instances owned by customers. TMF637 tracks the customer's installed base and subscription state.

The TMF Open API for managing the service inventory, which records all active service instances (CFS and RFS) and their parameters, relationships, and state.

The TMF Open API for managing the resource inventory, which records all physical, logical, and virtual resource instances, their attributes, and interconnections.

The TMF Open API for activating, configuring, and deactivating services on the network. TMF640 provides a standardised interface between SOM/ROM and the activation layer.

The TMF Open API for managing service orders throughout their lifecycle. TMF641 defines the structure for service order items, actions, and state transitions, bridging commercial orders (TMF622) to resource-level fulfilment.

The TMF Open API for checking service availability and feasibility at a given location or for a given customer. TMF645 is used during the pre-order phase to confirm that requested services can actually be delivered.

The TMF Open API for managing the quotation lifecycle: creation, pricing calculation, negotiation, approval, and acceptance. TMF648 supports both simple consumer quotes and complex multi-site enterprise proposals.

The TMF Open API for managing resource orders that instruct the network to allocate, configure, or release resources. TMF652 is the interface between SOM/ROM and resource management systems.

The TMF Open API for managing service problems that are identified through alarm correlation, performance degradation, or customer-reported issues. TMF656 links faults to impacted services and drives resolution workflows.

The TMF Open API for defining and monitoring service quality objectives and thresholds. TMF657 supports SLA compliance tracking by comparing actual service performance against agreed targets.

The TMF Open API for the basket: offerings selected and priced before checkout. In consumer sales it does the job a quote does in business sales.

The TMF Open API for managing customer accounts, including billing accounts, financial accounts, and settlement accounts. TMF666 covers account creation, hierarchies, and account-level contact and payment method management.

The TMF Open API for the roles parties play — customer, contact, user, partner — kept separate from the party itself.

The TMF Open API for managing geographic sites and locations. TMF674 is used in address validation, site surveys, and multi-site ordering to ensure services are linked to verified physical locations.

The TMF Open API for managing customer bills and invoices. TMF678 supports bill retrieval, applied payments, bill dispute handling, and integration with downstream revenue management systems.

The TMF Open API for determining whether a specific product offering can be sold to a customer at a given location or context. TMF679 checks eligibility rules, availability constraints, and technical feasibility before quoting.

The TMF Open API for risk assessments of a party, an offering, a basket or an order — the interface a credit or fraud check is requested through.

The TMF Open API for sales leads and, since v5, sales opportunities. Opportunity support is recent and still maturing, so it is best treated as emerging.

The eTOM end-to-end business flow from issue detection or customer complaint through to resolution and closure. It encompasses fault management, diagnostics, field dispatch, resolution, and root-cause analysis.

The 5G core function that forwards subscriber traffic between the radio network and the data network, under instruction from the SMF. It applies QoS, packet inspection and usage reporting. Because the UPF can be placed centrally or at the edge (close to an enterprise site or MEC platform), its placement is a design decision with direct latency, cost and product consequences.

Virtualised Infrastructure Manager: the MANO component that manages compute, storage, and networking resources in the NFVI. VIM allocates virtual resources to VNFs and monitors infrastructure utilisation. OpenStack is a common VIM implementation.

A network function (e.g. firewall, router, load balancer) implemented as software running on virtualised infrastructure rather than on dedicated hardware. VNFs are deployed and managed through the MANO framework.

The MANO component responsible for the lifecycle management of individual VNF instances: instantiation, scaling, healing, and termination. VNFM operates under the coordination of the NFVO.

A commercial model where a telecom operator sells network capacity, connectivity, or service components to other operators or service providers rather than directly to end-users. Wholesale requires dedicated BSS capabilities for inter-carrier settlement and capacity management.

A device fetches its own initial configuration from the automation layer on first boot — identity, software image, base config — with no engineer logging in. It removes the manual Day-0 step and makes site deployment repeatable; it depends on the automation layer already holding a correct intended configuration for that device.