Please join us tomorrow at the change seminar where I will present work exploring the universal application design space for ICTD. This session will explore the similarities and differences between IVR, SMS, and USSD and how they relate to creating bottom of the pyramid mobile applications. I will present a basic USSD library for prototyping USSD applications. *Abstract* In this presentation we argue for the use of Unstructured Supplementary Service Data (USSD) as a platform for universal cell phone applications. We examine over a decade of ICT4D research, analyzing how USSD can extend and complement current uses of IVR and SMS for data collection, messaging, information access, social networking and complex user initiated transactions. Based on these findings we identify situations when a mobile based project should consider using USSD with increasingly common third party gateways over other mediums. This analysis also motivates the design and implementation of an open source library for rapid development of USSD applications. Finally, we explore three USSD use cases, demonstrating how USSD opens up a design space not available with IVR or SMS.