The Pictuerphone pioneer of the 1970s, AT&T, is still one of the biggest producers; its unit goes for $1080. Phone from Marconi ,Alcatel, Casio and Britain's BT are also in or headed for the showrooms. So who's buying? Businesses should, says Marconi rep Roddy Poo, "because it is much cheaper than video conferencing." But no one new talk numbers sold.