In this paper we discuss the prospects of using marker based Augmented Reality for context aware applications on mobile phones. We also present the UMAR, a conceptual framework for developing Ubiquitous Mobile Augmented Reality applications which consists of research areas identified as relevant for successfully bridging the physical world and the digital domain using Mobile Augmented Reality. A step towards this we have successfully ported the ARToolkit to consumer mobile phones running on the Symbian platform and present results around this. We also present three sample applications based on UMAR and future case study work planned. Categories and Subject Descriptors H.5 [Information Interfaces and Presentation]: Multimedia Information Systems General Terms Human Factors, Experimentation, Design Keywords Augmented Reality, Pervasive Computing