Sims (back) was activated Tuesday from the 15-day injured list, Charlie Goldsmith of The Cincinnati Enquirer reports.
Sims will join the Reds' bullpen Tuesday against the Rays -- a day earlier than expected -- after logging three solid minor-league rehab appearances at Triple-A Louisville. He's battled a lot of injuries in recent seasons, but the 28-year-old right-hander could quickly rise into a prominent setup role if his health cooperates.