A network camera, a program and a network system, which can perform voice communications by comfortable operations. The network camera can transmit an image to at least one terminal capable of performing a voice communication in a half duplex manner, and can perform a voice communication with the terminal. The network camera creates and transmits page information to the terminal. This page information displays: a button indicating the possibility of outputting the voice when it receives a demand from the terminal, in case the voice output is not inhibited and in case another terminal is not outputting the voice; a button indicating the voice outputting, in case the voice output is done; and a button indicating a temporary voice output inhibit while another terminal is transmitting the voice, so that the page information can be altered, when depressed, to another button display in accordance with the change in the communication state.