IP Multimedia Subsystem (IMS) is well known for its combination of the capability of universal coverage of mobile network and rich application development environment of IP network. IMS has been welcomed by both industry and academic society, becoming the first choice of the Next Generation Network (NGN) technologies. This paper describes the design and implementation of three IMS teaching lab experiments, based on open source Doubango project. The lab experiments are designed for graduate students and senior undergraduate students to learn how to design and implement an application for IMS user equipment (UE). The paper analyzes the requirements of the experiments, presents an object-oriented software solution, and explains its Doubango-and-OpenIMSCore-based implementation.