Apparatus and methods are directed to calibrating a delay within a wireless access point for determining a position of a mobile station. One method includes receiving an initial packet at an eavesdropping device, receiving a response packet, sent by another entity, at the eavesdropping device, computing a time difference based upon the packet arrival times, and providing the time difference to a position determination entity. Another method includes providing a request to appropriate eavesdropping devices to send information, receiving, from each appropriate eavesdropping device, a time difference which represents a difference in a time of arrival of a packet transmitted by the wireless access point and a time of arrival of a packet transmitted by the mobile station, determining a processing delay estimate based upon the time differences, and determining a position of the mobile station based upon the processing delay estimate and the received time differences.