Position: Convergent Online Charging
Modular, flexible, and scalable, ZTE Online Charging System meets all operators´ demands for next generation charging.
Prepaid subscription accounts for a large portion of many operators´ overall income and continues to grow exponentially all over the world. However, due to the technical limitations, prepaid subscribers have typically not enjoyed as many value- added services as postpaid subscribers. The constraints based on the user´s payment mode are very likely to raise churn level and bring down ARPU.
Prepaid and Postpaid Convergence (PPC) is becoming an operator requirement. By combining the traditional call control mechanism from Intelligent Networks (IN) and the flexible charging functions of the billing system, ZTE´s Online Charging System (OCS) is ideal for operators looking to implement PPC without a big impact on the existing infrastructure.
ZTE launched OCS in November 2004 to reduce both the high customer care costs associated with hot-billing based prepaid solutions and high investment and risks for IN-based prepaid solutions. The OCS breaks down online charging functions of billing collection points: - SCP (Service Control Point), MSC (Mobile Switching Center), SMSC (Short Message Service Center) and MMSC (Multimedia Message Service Center) - and converges them into an independent and unified online charging platform.
ZTE OCS uses a data model similar to hot-billing, which enables OCS to deliver prepaid and postpaid services through subscriber data sharing. Besides traditional voice services, the OCS also mandates integrated charging for content and data for 3G, WLAN, IPTV and WIMAX services.
Currently, there are three billing modes available for prepaid and postpaid. The most commonly used is the prepaid platform plus the billing system, which provide online prepaid charging and offline postpaid charging respectively. Separated billing approaches and platforms require heavy initial investment and cannot provide a single view of customers´ accounts, as well as lack of abilities to provide bundle and cross products. The second mode is a hot billing system, which performs converged prepaid and postpaid charging in near real-time but still could not avoid high risk of overdraft. In contrast, OCS overcomes these shortcomings and enables operators to maximize revenue potential from users. The comparison of these three billing modes is shown in Fig.1.
Fig. 1 Comparison of three billing models
Using the OCS based prepaid service, charging is no longer controlled by the SCP. Instead, SCP sends billing requests to OCS via a Diameter Credit Control Application, which executes the billing logic and returns the results to SCP to complete the entire online billing process. Through this real-time interaction between billing and service control, the back-and-forth operations track service usage and update the account balances in real time. The functional units of OCS in a GSM environment are illustrated in Fig.2.
Fig. 2 A typical OCS call flow
1. After receiving the Initial Detection Point (IDP), the SCP determines subscriber-specific service logic, validates the called number and judges whether the related OCS is overloaded.
2. The SCP sends related information and processing results to the OCS through the initial CCR (Credit Control Request) to authorize credit for resource usage.
3. Based on the information from the SCP, the OCS fulfills functions of account authentication, rating, backward reckoning and quota reservation and notifies the SCP of the allowable duration through CCA (Call Control Agent).
4. The SCP sends Apply Charging (AC) to Mobile Switch Centre (MSC) / Service Switching Point (SSP) instructing MSC/SSP to connect and monitor this call.
5. After receiving Apply Charging Report (ACR) provided by the MSC/SSP, the SCP sends updated CCR to OCS with a report of the elapsed time and requests the OCS to reserve a new quota.
6. The OCS carries out backward reckon and quota reservation according to the reported CCR and notifies SCP of the allowable duration through CCA.
7. After the call is completed, the SCP receives ACR from MSC/SSP and sends the final CCR to the OCS to report the elapsed time.
8. The OCS deducts fee according to the reported CCR and returns the CCA to the SCP.
ZTE OCS has a wide variety of features, which includes but not limited to:
Owing to the feature-rich and carrier-grade design, ZTE OCS is dedicated to bringing countless benefits to operators.
Based on the interpretation of customer, product, account, etc in the new billing model of the telecom industry, ZTE redefines related billing entities, sets up a customer-centered billing model and forms a unified customer view, converging prepaid and postpaid, fixed and mobile, voice and data services capable of sessions and events based billing functions. OCS lays a solid basis for fast service rollout and quick investment return.
ZTE OCS supports online charging for both prepaid and postpaid. Since the charging is separated from call control, and hides the technical details of the bearer network, it is possible for prepaid subscribers to use all the services and enjoy the same user experiences as postpaid subscribers. Prepaid and postpaid are only different in payment mode. The same level of services ensures rising of ARPU of prepaid and falling of prepaid churn rate.
Based on the proven data model of ZTE´s offline billing system, the OCS supports flexible rating with fast introduction of new tariff models. The multi-element, multi-object and multi-mode billing approach helps to implement the customer-centered and market-oriented service development strategy.
Based on user balance and credit control, OCS supports quarter blocking, forward algorithm and backward algorithm to realize online call charging and processing. The Advice of Charge (AOC) supplementary service allows the served user to be informed of usage-based charging information at call set-up time, during the call, and at the end of the call.
The flexible modular architecture of ZTE OCS ensures a quick and seamless mesh with existing infrastructure. This solution provides cost effective in-service capacity upgrade with zero downtime and ensures the carrier-grade availability to which operators are accustomed.
ZTE OCS provides customers with flexible payment methods which can help win customers and inspire loyalty. Supporting real-time transactions, it can help operators recognize revenues and avoid revenue leaks. Modular, flexible, and scalable, ZTE OCS meets all operators´ demands for next generation charging.
