a method and apparatus to enable ip networking for mobile hosts without requiring changes to be made to the tcp / ip stack in the operating system installed on the mobile hosts . the apparatus is an “ intelligent device ” that can be installed on or connected to a mobile host , and may comprise a software - only logical module , physical hardware , or a combination of both . to a mobile host , the intelligent device emulates a network interface such as an ethernet card or a telephone modem . the intelligent device appears to an access network just like any regular ip host connected to the access network through a physical network interface device . the intelligent device handles all mobile networking functions for the mobile host , and may control multiple different physical network interface devices to enable a connection to the “ best ” access network available to the mobile user at his location .