In 1991, Sims joined ESPN as a play-by-play announcer for college basketball, and added college football in 1998. He primarily called Big East contests on the ESPN Plus regional network.
In addition to his Sunday Night Football radio gig, Sims also calls college basketball for Westwood One, with his most notable call to date being the George Mason-UConn regional final in 2006 (where #11 seed George Mason upset top-seed Connecticut to become the second #11 seed in history to reach the Final Four).
Prior to taking the permanent play-by-play position on Sunday Night Football, Sims was the #2 broadcaster for Westwood One's Sunday afternoon NFL doubleheader. He replaced Joel Meyers on the Sunday Night Football game in 2006.
While working in other sports, he occasionally provided Major League Baseball play-by-play for ESPN and did an internet radio show for MLB.com. In , he took the opportunity to return to baseball full-time as part of the Seattle Mariners television broadcast.One of the few African-American broadcasters in the sport, he is also perhaps the only one of that group not to have played in the major leagues.

