Drew this up ages ago from a customer's radio while it was here. The chip is a custom part meant to be used in a suburban-home intercom system, with a single Ding on the yellow wire for the front door, a double ding-dong on the brown wire for the back door, and a third noise that I can't remember when you ground the green wire. And that's why nobody can find this chip. It was a custom deal, never was licensed to any second sources. Best I can tell the date code says 1985. Probably not useful unless you stumble across one of these.
73
