A communication device controlling method, for controlling a communication device including a first subscriber identification and a second subscriber identification when a process of a data call established with the first subscriber identification is in a suspension, comprising: (a) receiving, by a processor of the communication device, a request to establish a mobile terminated (MT) call with the second subscriber identification; and (b) resuming, by the processor, the process of the data call from the suspension before an instruction of accepting or rejecting the request is received if the MT call is packet-switch based.