PHS TERMINAL POSITIONAL INFORMATION OBTAINING METHOD AND DEVICE THEREFOR

摘要

PROBLEM TO BE SOLVED: To track the position of a PHS terminal even at the time of getting on an object moving fast such as a vehicle by momentarily transferring ID of a CS base station through the use of an originating subaddress within the D-channel of an ISDN line network. SOLUTION: A means 21 calling to the side of a positional information obtaining device is regularly started and a subaddress means 22 in the ISDN network sets the identification ID of a CS base station of a highest electric field intensity at the time. A line network connecting means 8 on a positional information obtaining device called from an ISDN line network 5 investigates the presence/absence of the identification ID of the CS base station to the originating subaddress within the D-channel of the network 5 by a means 23, obtains at the time of presence, immediately sends a signal meaning the rejection of call incoming to the ISDN line network and transfers obtained identification ID to a positional information obtaining device 9. The positional coordinate of a CS base station is retrieved from a base station positional coordinate data base by setting this identification ID as a retrieving key and a positional coordinate display means 11 displays the positional coordinate.