With the emergence of mobile multimedia services, such as unified messaging, click to dial, cross network multiparty conferencing and seamless multimedia streaming services, the fixed-mobile convergence and voice-data integration has started, leading to an overall Internet-Telecommunications merger. The IP Multimedia Subsystem (IMS) is considered as the next generation service delivery platform in this converge communication world. It consists of modular design with open interfaces and enables the flexibility for providing multimedia services over IP technology. At parallel this open based emerging technology has security challenges from multiple communication platforms like IP, SIP and RTP. In this article our objective is to develop security model to protect IMS Service Delivery Platform (SDP) from different time independent attacks e.g. SQL injection and media flow attacks. These attacks ultimately downfall the value added services. At the end we shall present the performance results at Fokus Fraunhofer Testbed to see the proposed solution for real world applications.