Too expensive to scale. Recorded greetings and directories have been around for a long time. Just having "Welcome to XYZ Co. For sales press 1, for support pres

Too expensive to scale. Recorded greetings and directories have been around for a long time. Just having "Welcome to XYZ Co. For sales press 1, for support press 2, for a staff directory press 3" etc. is fairly effective in rebuffing robocalls as only human spammers bother pressing digits.