A communication terminal apparatus and its control method which allow the parallel execution of a plurality of communications with use of a plurality of data channels. The terminal apparatus comprises an image main controller and a voice main controller which can be operated independently of each other, two network controllers operated as associated with the operations of these image and voice main controllers respectively, two image transmission control circuits which are operated independently of each other, and an image file capable of storing image and voice data, thereby realizing the simultaneous execution of image and image communications and the simultaneous execution of voice and voice communications on a duplex communication basis.