There are many technical solutions for indoor positioning. The main limitations, whatever the technology, are based on problems of signal propagation: obstacles, absorption, reflections and so on. In indoor environments, which are the most complex in this field, current solutions all have significant limitations. The result is unsatisfactory performance, except under specific conditions which then remain niches. The combination of the symbolic approach (by zone of very high probability of presence), which combines simplicity of implementation and reliability, is the trigger, in our view, for large-scale deployments. This is possible with the integration of the required electronics in security electric equipments (mandatory and normalized all over the world for public buildings). After outlining the difficulties of conventional approaches (models) in detail, we present the principle of the symbolic approach and the impact of very noisy signals, as is common indoors. Performance obtained in real environments is then provided.