Acoustic modems were obsolete by 1980. Smartmodems of the 1980s didn't use sound to transmit data, they modulated an electrical signal directly on the line. Th

Acoustic modems were obsolete by 1980. Smartmodems of the 1980s didn't use sound to transmit data, they modulated an electrical signal directly on the line. They were silent (except during call set up, but that was just a "Monster Rancher" to confirm set up was proceeding in the normal way) Telephone handsets used data to transmit sound.