It’s only just occurred to me that what I’ve always referred to as an acoustic coupler is a modem. The acoustic coupler is just the bit of the modem that connects to the phone line. Don’t think I’ve ever seen one in person, but I’ve watched Matthew Broderick use one to play global thermonuclear war. 😀 I guess if you’re someone who was used to having a phone and acoustic coupler modem and that gets replaced by a modem that plugs in to the phone line directly, why not keep the phone where it is and tuck the new modem under it.