We have developed a multi-standard GNSS (Global Navigation Satellite System) receiver including the simultaneous detection of the four current constellation: GLONASS, Galileo and Beidu. The technique used is sub-sampling, which simplifies the receiver architecture. A special feature of our implementation is that the "indoor" aspect is already taken into account at the design stage. The latter is further considered by the use of pseudo-satellites ("pseudolites") of particular architecture, the "Grin-Locs". In our case, we have adapted the frequency bands of the various constellation in order to include the associated indoor constraints in our sub-sampling design. This article presents the problem if indoor using Grin-Locs and the performances obtained with our multi-standard sub-sampling receiver in phase measurements of signals for indoor positioning