Recent trends in mobile development have driven smartphones to become multipurpose devices engineeredto improve day to day activities. Due to their multi-functionality, smartphones have gradually evolved to replace traditionalinstruments as an all-in-one digital companions, but remain constrained by their sensory awareness. To provide userswith a richer experience, mobile devices need to be context-aware in order to adapt the interaction process accordingto changing environmental events. One of the key components for a device to be context-aware is positioning, howeverGPS, which is essential to the positioning capability of mobile devices outside, is not available under obstructions suchas roofs or tunnels. The purpose of this paper is to propose an extensible, open standard for indoor navigation capableof combining multiple sensor technologies in order to reduce the drawbacks of any individual one, lowering the barrierto industry-wide adoption.