Telecom Industry encounters rapid changing operations environment, which makes it urgent to innovate in its original Operations Supporting Systems. In order to attract more customers and provide higher quality of services, Service Providers rollout all kinds of new services such as digital audio and video services which result in different usage data record formats increasing very quickly. How to bill for these new records in accurate has become a hot problem which the original Telecom Billing System is facing. Telecom operators are finding new billing solutions to suit these changes. Furthermore, the performance of real time is also taken into account. This paper describes a simulative platform based on RT-Linux that aims to use OSS/J IP Billing API to integrate an open source billing system and solve the problem of different usage data record formats billing. We present the framework of the platform, build a trial network of VoIP and design a real time billing module to collect usage data records for the billing system.