PURPOSE: To obtain a data link establishing method which has superior responsiveness by allowing a radio base station to send such a special request to establish a data link that some terminal should answer when receiving it to a mobile terminal which neither transmits nor receive a telegraphic message for a long period.

CONSTITUTION: When a request (1) to establish the data link DL is transmitted by using a transmit channel TX of the radio base station 2, the mobile terminal device 3 receives the request (1) by a receive channel RX and makes no answer unless there is a telegraphic message to be sent to the base station 2 an internal processing time (3) later. The base station 2 sends a request (4) to establish the DL to the next device 3 when there is no answer within a specific time. The base station 2 sends such a special request (5) to establish the DL that a receiving terminal should answer when receiving it to the device 3 which neither transmits nor receives a telegraphic message for a long period. The terminal 3 receives the request and sends a DL establishment answer (2) the internal processing time (3) later to show that it is in the service area of the base station 2. The base station confirms its presence and sends a DL establishment request (4) to the next mobile station.