Abstract: A telephone apparatus enables the approximate simultaneous transmission and reception of audio interleaved with image and graphical annotation signals, in data packet form, over an analog line which connects the apparatus to a switched telephone network. The audio data packets are transmitted at a periodic rate, during a first time interval, and the image and annotation data packets are transmitted during a second time interval, following the first time interval, enabling the simultaneous output of voice, image and annotation data at the receiver site. Control data packets, as needed, are also transmitted during the second time interval for end-to-end apparatus control. One feature enables the transmission of audio data packets at a first periodic rate, when in an image transmission mode, and at a second periodic rate, faster than the first periodic rate, when not in the image transmission mode.