A system and method determines a geographic position of a mobile device in communication with an IP-based wireless telecommunications network. A wireless connection between the mobile device and the IP-based wireless telecommunications network is established when the mobile device registers with a network controller (NC) through an access point (AP). When a geographical position is needed for the mobile device (e.g., a 911 call), messages are exchanged between the NC and the SMLC, where the SMLC retrieves information from a database that is used to identify the geographic position of the mobile device. The database can store a variety of information related to mobile devices such as: last known position, IP address, MAC address, device or subscriber identifier, last CGI, etc. The geographical position is communicated back to the NC, which can then forward the position information to a switch for processing such as for 911 calls.