Locating a smartphone at the centimeter-level has significant implication for potential indoor location services and applications compared with existing coarse-grained solutions. In this paper, we propose Guoguo ecosystem to fill the longlasting gap of smartphone-based indoor localization. Guoguo consists of a constellation of low-complexity anchor network that enabling fine-grained localization by leveraging modulated acoustic beacons. We propose algorithms to improve its robustness, coverage, accuracy, and refresh rate. Our prototype shows centimeter-level localization accuracy and promising for real deployment and application. Such results are expected to make smartphone indoor localization available in our daily activities.