The IP Multimedia Subsystems (IMS) that features in Next Generation Networks (NGN) offers the application developer (third party) abilities to map out applications over mobile telecommunication infrastructure. The IMS comes about with APIs useful for mobile application developers to create applications to meet end-users' demands and comply with the provider's infrastructure set up at the same time. Session Initiation Protocol (SIP) is a signaling protocol for this architecture. It is used for establishing sessions in IP network, making it an ideal candidate for supporting terminal mobility in to deliver the services with improved Quality of Services (QOS). The realization of IMS's virtues as far as software design is concerned is faced by lack of standardizations and methodologies throughout application development process. In this paper, we report on progress on ongoing research by our group toward putting together a platform as a testbed used for NGN application development. We examine a novel component based development model used for SIP based mobile applications. The developed model is to be used as framework for general purpose application development over the testbed. We apply this model on MObile Mass EXamination (MOMEX) system that is an application attracting the interest of educational authorities around the world due to its potential convenience.