Mobile messaging services like SMS, MMS and wireless instant messaging services have become the major revenue source of the wireless data services. Compared with the online web access model, messaging access is more preferred in the wireless environment because messaging systems work in an asynchronous way and can tolerate intermittent connectivity. Current mobile messaging focuses on consumer applications, e.g., person-to-person communication. To leverage mobile message usage in mobile enterprise applications, iMMS (Interactive Multimedia Messaging Service) is proposed in this paper, which adds interactive features into MMS standard to provide rich and friendly user interface, local interaction and offline operation. In this paper, a message package based programming model is introduced to support interactive messaging application development. A design of an iMMS framework based on this programming model is presented. The architecture of the framework is also discussed. Finally a mobile workflow solution is given to show the implementation of a mobile enterprise application on the framework.