KYW News in Philadelphia used to keep a microphone live in the teletype machine as background sound for cutting news stories. They switched to a recorded teletype sound rather than live sounds due to announcers running to the machine, reading the story and immediately responding with swear words!
I think they still use the recorded sounds of the teletype machine on their news broadcasts.
http://www.youtube.com/watch?v=Dv9rrd3DYZM&feature=related
Just in case you meant a 15 instead of a 28