Telecommunication system for automatically locating by network connection and selectively delivering calls to mobile client devices

A system for telephone communication, comprising:

• an IP-LAN including an IP telephony server;
• a dual-mode communication device comprising first apparatus for conducting telephone calls on a cell-phone network, including a cell-phone number, and second apparatus for conducting telephone calls over the IP-LAN;
• a publicly-switched telephone network (PSTN) having a trunk connection to the IP telephony server;
• and
• a PSTN-connected routing server;
• wherein the IP telephony server, upon connection of the dual-mode communication device to the IP-LAN, assigns a temporary IP address to the connected device and informs the routing server of the connection and a destination number for the IP telephony server, and wherein the routing server then routes calls for the cell phone number to the IP telephony server, which in turn routes the calls on the IP-LAN to the temporary IP address.

An IP Local Area Network (IP-LAN) system, comprising:

• an IP telephony server connected on the LAN and to a publicly-switched telephony trunk;
• and
• control routines executing on the IP telephony server;
• wherein the IP telephony server assigns a temporary IP address to a cell phone-capable device connecting on the LAN, and communicates the fact of connection and a destination number for the IP telephony server to a PSTN-connected routing server.

A method for minimizing cell phone charges for an organization having multiple sites, comprising steps of:

• (a) providing an IP-LAN at at least one organization site, the LAN having a PSTN-connected IP server;
• (b) providing at least one dual-mode communication device for use by organization personnel, the device capable of connection and communication on both a cell-phone network and on the LAN;
• (c) assigning a temporary IP address to the one or more dual-mode communication devices upon connection to the LAN;
• (d) associating the IP address with the cell phone number of the dual-mode communication device at the IP server;
• (e) communicating the cell phone number and a destination number for the IP server to a PSTN-connected router;
• and
• (f) routing calls for the cell phone number to the dual-mode communication device via a cell phone network during time the dual-mode device is not logged on to the LAN, and to the IP server for routing on the LAN during time the device is logged on to the LAN.