On the mobile communication terminal 100 side, when the VOIP communication application stored in the storage unit 104 is activated in accordance with an instruction from the user (step S101), the application activation judging unit 107a judges that the VOIP communication application has been activated. Upon the judgment, the control unit 107 selects a cycle (for example, 1.152 seconds: code F10) that is shorter than 5.152 seconds, generates an EISP signal based on the selection, and transmits the generated EISP signal to the base station 200 via the transmission unit 102 (step S102). After this, upon receiving an ACK signal, the control unit 107 starts to activate the reception unit 103 at the cycle of 1.152 seconds to receive the report signal at the cycle of 1.152 seconds (step S105).