Real-time Transfer of Tariff Information

Description

Real-time Transfer of Tariff Information (RTTI) is a critical component within the 3GPP charging architecture, specifically defined for CAMEL (Customized Applications for Mobile networks Enhanced Logic) and other online charging systems. It operates as a protocol and data exchange framework that facilitates the immediate communication of tariff details—such as service costs, rating groups, and billing parameters—between network entities like the Service Control Point (SCP) or Online Charging System (OCS) and the network elements executing the service (e.g., MSC, SGSN, GGSN). This real-time capability is essential for services where the cost must be known and authorized before or during service delivery, preventing revenue leakage and enabling prepaid and convergent billing models.

The architecture of RTTI is integrated into the signaling and control plane. When a subscriber initiates a chargeable event (e.g., a voice call to a premium number or a mobile data session), the network element queries the charging system via standardized interfaces like CAP (CAMEL Application Part). The charging system responds with the applicable tariff information, which may include the price, currency, and validity period. This information is then used to authorize the service, apply the correct charging rate, and potentially notify the subscriber via mechanisms like Advice of Charge (AoC). The process ensures that the billing is synchronized with service usage, supporting complex tariff plans, promotions, and inter-operator settlements.

Key components involved in RTTI include the Charging Trigger Function (CTF), which detects chargeable events; the Online Charging System (OCS), which holds tariff data and performs rating; and the CAMEL service environment, which provides the intelligent network framework for real-time control. RTTI's role extends beyond simple billing; it is foundational for service differentiation, enabling operators to offer tailored, real-time charging for value-added services, roaming scenarios, and emerging data services, thereby enhancing customer experience and operational efficiency.

Purpose & Motivation

RTTI was created to address the limitations of traditional batch-based or post-event billing systems, which were inadequate for the dynamic, real-time services emerging in mobile networks. Prior to its standardization, charging for premium services or prepaid accounts often relied on delayed data exchanges, leading to inaccuracies, revenue loss, and poor customer experience due to unexpected charges. The growth of intelligent network services like CAMEL demanded a mechanism to authorize and tariff services in real-time, ensuring subscribers could be charged accurately at the moment of consumption.

The primary problem RTTI solves is the need for immediate tariff resolution and credit control. For prepaid subscribers, it enables real-time balance checks and deductions, preventing service usage beyond available credit. For postpaid and convergent billing, it allows for instant application of complex tariff rules, such as time-of-day rates or service-specific bundles. This capability is crucial for operator revenue assurance, as it minimizes the risk of unpaid usage and supports sophisticated business models for content providers and third-party services.

Historically, RTTI's development in 3GPP Release 8 and its continuation through subsequent releases was motivated by the evolution towards all-IP networks and the increasing variety of chargeable services, from SMS to mobile broadband. It provides a standardized, interoperable framework that replaces proprietary solutions, facilitating seamless roaming and multi-vendor network deployments. By ensuring real-time tariff transparency and control, RTTI underpins the commercial viability of modern mobile services.