Charging origin

Description

The Charging origin is a concept defined in 3GPP specifications 32.250 and 32.272, which are part of the charging management framework. It represents a nominal reference point that defines the point of origin of a connection for charging purposes. In essence, it is the logical location or functional entity where a chargeable connection is considered to start. This allows charging systems to correlate usage records and apply the correct tariffs based on where the connection originated. The concept is fundamental to the Charging and Billing domain, ensuring that network operators can accurately bill subscribers and interconnect partners for services used.

The need for a precise charging origin arises from the complexity of modern mobile networks, where a single service session may traverse multiple network elements and domains. For example, a data connection might be initiated by a UE in a visited network, routed through a home network, and access services provided by a third party. The charging origin helps to determine which network entity is responsible for generating the charging data and how to handle the charging in roaming and inter-operator scenarios. It is closely linked to the Charging Trigger Function (CTF) and the Charging Data Function (CDF) as defined in the 3GPP charging architecture (TS 32.240). The CTF generates charging events based on triggers, and the Charging origin helps to contextualize these events.

In the technical specifications, Charging origin is often used in the context of charging for services like messaging, voice calls, or data sessions. For instance, in TS 32.250 (Charging management; Circuit Switched (CS) domain charging), the charging origin might refer to the Mobile Switching Center (MSC) or Gateway MSC (GMSC) that originates the charging record. In TS 32.272 (Charging management; Push-to-talk over Cellular (PoC) charging), it could refer to the PoC server that initiates the charging. The exact definition may vary slightly depending on the specific service or domain, but the core idea remains: it is a reference point that anchors the charging process.

The implementation of Charging origin is typically manifest in charging data records (CDRs) and charging events. When a connection is established, the network element that detects the start of the connection generates a charging event and includes the Charging origin information. This information is then passed to the charging system, which uses it to determine the correct rating and billing. The Charging origin can be represented as an identifier, such as a network element ID, an address, or a logical name. In some cases, it may be a combination of parameters that uniquely identify the origin. The concept is standardized to ensure interoperability between different vendors' equipment and across different releases of the 3GPP specifications.

From a broader perspective, the Charging origin is part of the charging architecture that has evolved from Release 8 onwards. It supports the principles of service-based charging, where charging is decoupled from the underlying bearer and can be applied flexibly. As networks move towards 5G and beyond, charging mechanisms become more granular and dynamic, and the Charging origin continues to play a role in identifying the source of chargeable events. However, the term itself has remained stable over the releases, indicating its foundational nature.

Purpose & Motivation

The Charging origin exists to provide a clear, standardized reference for the starting point of a chargeable connection or service. Without a well-defined origin, charging systems would struggle to determine which network element should generate charging records and how to correlate them. In multi-vendor, multi-domain networks, having a common understanding of where charging starts is essential for accurate billing and revenue sharing. The concept solves the problem of ambiguity in charging responsibility, especially in roaming and interconnect scenarios where multiple operators are involved.

Historically, before the formalization of the Charging origin in 3GPP Release 8, charging systems relied on proprietary or less precise definitions. This led to inconsistencies and disputes between operators. The introduction of a standard concept helped harmonize charging processes and enabled seamless roaming. It also facilitated the development of converged charging systems that can handle multiple services and access types.

The Charging origin continues to be relevant as networks evolve towards 5G and virtualization. In virtualized environments, network functions can be instantiated dynamically, and the Charging origin helps to identify the logical function responsible for charging, even if its physical location changes. This supports the flexibility and scalability required for modern networks.