embodiment of fig4 location information is obtained with reference to one or more of wlan access points the format of fig4 includes a unit id field 401 which contains an identifier for the wireless unit it can be in the form of identifier such as a telephone number the format of fig4 includes a time field 403 which indicates the time period during which the mobile game unit will be available for game play in the embodiment of fig4 the time period is specified as a number of minutes following the sending time of the session ready message in other embodiments the time available for play could be specified in terms of an end time in other embodiments the time may be indefinite in which case the player is maintained in the list of available players until the player logs out the message format of fig4 includes a service set identifier ssid field 405 ssid field 405 contains a unique identifier for each wifi access point within range of the mobile game unit finally the format of fig4 includes a signal strength field 407 which contains the signal strength measured by the mobile game unit for each wlan access point within range of the mobile game unit fig5 illustrates a session ready message format according to another embodiment of the present invention the message format.