A secondary directory telephone number (SDN) is assigned either to each voice over IP (VOIP) IP port utilized by subscribers or to each public safety access point (PSAP). The SDN, MAC address of the IP port accessed by a subscriber, and geographic location of the SDN or MAC address are stored in a database. This information is accessed by the PSAP based on SDN or MAC address to obtain the location of a VOIP subscriber to facilitate providing emergency services in response to a 911 call by a VOIP subscriber.