The present invention is directed to a method and an apparatus for use in a cellular communication system. Specifically, the present invention is directed to a method comprising: transmitting, to one of WLAN Terminations (WTs), a first indication to wake up WLAN module of the UE; if no response for the first indication is received from the one of WTs during a first time duration, transmitting, to all of the WTs, a second indication to wake up the WLAN module of the UE; and if no response for the second indication is received from any of the WTs during a second time duration, transmitting, to a mobility management entity (MME), a third indication related with absence of the UE, and an apparatus therefore.