Charged Party

Description

The Charged Party is a fundamental concept in 3GPP charging architecture, representing the entity that is financially responsible for a chargeable event. A chargeable event is any activity that utilizes network resources or services and can be subject to charging, such as a voice call, data session, or SMS. The Charged Party may be the user who initiated the event, a third party who agrees to pay on behalf of the user, or even a network operator in certain settlement scenarios. This concept is critical for determining who gets billed and ensures that charging systems can correctly attribute costs.

In the 3GPP charging framework, the Charged Party is identified during the charging process. For example, in online charging, the Charging Trigger Function (CTF) reports the chargeable event to the Online Charging System (OCS), which then determines the Charged Party based on subscription data or service context. The OCS may interact with the Charged Party's account to reserve and deduct credits. In offline charging, the CTF generates Charging Data Records (CDRs) that include the Charged Party identity, which are then processed by the Billing Domain (BD) to generate invoices. The Charged Party can be different from the served user; for instance, in reverse charging scenarios, the called party pays for the call.

The Charged Party concept is defined in 3GPP TS 21.905 (Vocabulary) and is used across numerous charging specifications, including TS 32.240 (Charging architecture and principles), TS 32.250 (Circuit Switched domain charging), TS 32.251 (Packet Switched domain charging), and TS 32.260 (IP Multimedia Subsystem charging). These specifications detail how the Charged Party is determined, how it is included in charging records, and how it interacts with charging systems. The Charged Party may be identified by an IMSI, MSISDN, SIP URI, or other identifiers, depending on the service and domain.

The Charged Party is essential for supporting various business models, such as prepaid, postpaid, and sponsored data. It enables operators to offer flexible charging options, including charging the sender or receiver of a message, splitting charges between parties, or charging a third-party sponsor. Without a clear definition of the Charged Party, charging systems would not be able to correctly allocate costs, leading to revenue leakage or incorrect billing. Therefore, the Charged Party is a cornerstone of 3GPP charging architecture, ensuring accurate and fair billing for all stakeholders.

In summary, the Charged Party is the entity that pays for a chargeable event. It can be a user, a third party, or a network operator, and its identification is crucial for charging and billing. The concept has been stable since its introduction in Release 4 and continues to be fundamental in all subsequent releases, supporting evolving charging models in 5G and beyond.

Purpose & Motivation

The Charged Party concept exists to clearly identify who is financially responsible for a chargeable event in a telecommunications network. Before its formal definition, charging systems often assumed that the user initiating a service was always the payer, which limited business models and caused ambiguity in multi-party scenarios. The Charged Party addresses this by allowing the payer to be different from the user, enabling services like reverse charging, toll-free numbers, and sponsored data.

Historically, as networks evolved from circuit-switched to packet-switched and then to all-IP, the need for flexible charging grew. Operators wanted to offer differentiated services where costs could be borne by various parties. The Charged Party concept, introduced in 3GPP Release 4, provided a standardized way to represent this in charging records and online charging interactions. It solved the problem of revenue assurance by ensuring that every chargeable event could be traced to a responsible party, reducing disputes and fraud.

Today, the Charged Party remains essential for 5G and beyond, where new business models like network slicing and edge computing require even more granular charging. It enables operators to monetize services effectively and supports regulatory requirements for billing transparency.