Methods and systems for dynamically providing content complementary to a content being rendered on mobile devices based on determining a context of the device based on identifying an encoded unique audio identifier. The transmission and playback of the complementary content is synchronized with the currently rendered content by dynamically taking into account the context of a user operating the mobile device. The context of a user may be built from considering a piece of currently rendered content, characteristics of a profile of a vendor, characteristics of the individual user and/or the user's individual profile, date, time of day and/or further additional information. The context may further take into account the current position and/or location of the user as acoustically triangulated based on sending and/or receiving unique audio identifiers as a high frequency audio signal.