A method for geolocating a mobile computing device within an indoor environment. One embodiment may comprise generating a geolocation request audio signal by a speaker of a first device starting at a first point in time, receiving, by a microphone of the first device, a reply audio signal from a second device, and extracting, by one or more processors of the first device, information encoded in the reply audio signal. The method may further comprise estimating, by the one or more processors, a receipt time by the first device for the reply audio signal and calculating a first time of flight (TOF) using the first point in time and the estimated receipt time for a second audio signal. The first device may comprise a smartphone and the second device may comprise a beacon located at a known location in an indoor environment.