Abstract: A location mapping service (“LMS”) that allows the integrations of an IMS core with the location-based billing methods of a legacy core network. The LMS uses the estimated location of a mobile device during an IMS session in order to determine a Cell Global Identification (“CGI”) to associate with the session. The LMS then provides the determined CGI to the legacy core network, so that a billing gateway may determine the billing region to associate with the IMS session. The LMS thereby facilitates location-based billing for IMS sessions in the absence of actual CGI information.

Abstract: An E-CSCF receives a Session Initiation Protocol (“SIP”) invitation message initiating an emergency communication session from a calling device. The E-CSCF generates an information request message based on the received SIP message and sends the information request message to a location server. The location server determines a geographical location of the calling device and uses the geographical location to determine a destination emergency response center, such as a Public Safety Access Point (PSAP). The location server provides location information for the destination PSAP to the E-CSCF. The E-CSCF generates a modified SIP invitation message using the presence information and sends the modified SIP invitation message to an emergency services network where it is routed to the emergency response center.