A communication system includes a portable phone and a digital still camera. The user selects an image for transmission, and data indicating a frame number of the selected image is sent from the portable phone to the digital still camera. The portable phone sends a re-size instruction to the digital still camera. The digital still camera re-sizes the image data to reduce a data quantity thereof. The re-sized image data is sent from the digital still camera to the portable phone. The image data is sent from the portable phone via a network to a partner communication system. The image data has a reduced data quantity through the re-sizing and hence can be completely transmitted thereto in a relatively short period of time.