I worked in a call center for about a year and a half. On one of the campaigns we worked on, we transferred customers to other representatives at call centers representing schools. The number to dial out to the schools was always the same, but there was a three digit pin that went in a DTMF field.
Until now, I had no idea what DTMF stood for, or what it did other than route the call to the right school. I guess I always thought of it more as an extension. I was very interested to learn what the DTMF tone generator actually does.