Next to this batch of jidou hanbaiki or vending machines is an
ISDN phone. ISDN has been available on phone booths since the early
90s. These phones have an analog jack and an ISDN digital jack, make
sure you plug your laptop into the right one or Bad Things will happen.
Most ISPs can accept your connection as an ISDN connection for faster
speeds.

Of course, wi-fi and broadband/fiber-to-the-home have diminished the
importance and necessity of an ISDN connection, but at one time ISDN
was all the rage.

Did you know that the MP3 format was created to send audio over a dual
channel ISDN line? Using two 64 Kbps ISDN channels to create a single
128 Kbps, it was possible to transmit high-fidelity MP3 encoded audio
to a radio station, which changed the music industry in a way that was
not entirely planned for…