Believe it or not, the last time I used a modem I really did use an acoustic coupler! It was in a holiday cottage in deepest darkest rural Cornwall, where the only phone was an old rotary job wired into the wall, so I couldn't just unplug it and plug in my laptop.
in reply to The last time I used a dial-up modem was...
update: that was in 2001 IIRC
PPP setup and ssh key exchange takes a loooooooooooooooooong time at 300bps.
Since then I've done dialup on a mobile phone (9600bps) and using a 3G data card (300+ Kbps) but seeing that those are entirely digital there's no modem involved.