Where do you work? If you don't mind me asking. I'm always curious as to what companies use Erlang. My interest in he language came from Elixir, now I can't stop playing around with Erlang/Elixir.
We still use it for our new product (marketing tool for the music industry) but while it certainly works for us, we no longer have to support tons of simultaneous connections to our servers. The backend tech could almost be anything.
OpenX is a big user of Erlang for RTB.