Before getting his shot at the network level, Jim Nantz worked as the analyst on Utah Jazz local telecasts for a few seasons. His play-by-play partner on those games was Hot Rod Hundley.Here is a Jazz game from March 1985 called by this tandem. The game against the Chicago Bulls was televised by KSL-TV in Salt Lake City as part of a radio simulcast. Considering that he has been one of the preeminent play-by-play voices for the past few decades, I found it intriguing to hear a young Nantz as an analyst (essentially filling the old-fashioned color commentator role).
A season later, Nantz was serving as a play-by-play announcer on some regional NBA playoff telecasts on CBS.