A frictionless access control system and method providing ultrasonic user location are disclosed. The access control system authorizes users within proximity of an access point such as a door, based upon user information (e.g. credentials) sent in RF wireless messages from user devices carried by the users. When the users are authorized, the system instructs the user devices to transmit coded acoustic signals. An positioning unit at the access point includes an ultrasonic microphone array, which is located above the access point and detects the acoustic signals. The positioning unit determines an angle of arrival (AoA) of the acoustic signals at microphones of the array, and determines positions of the users relative to the access point from the AoA. In one implementation, pre-authorized users are granted access when the determined positions of the users are within an inner zone of the access point.