The function similar to “Call on Hold”, but in this case it is used during the video conference, by pressing the button, the video conference puts on hold mode.
Some telephones, depending on the brand and model, have the intercom function, which allows to begin communication by sending the signal. When the signal comes, the telephone set rings a signal different from the standard ring tone call. After that the telephone temporarily switches off from the telephone line and works as an intercom.