Casali, 27, was with the Rays from Opening Day and batted .168 with seven home runs and 20 RBIs until he was optioned to Durham on Aug. 5. He leads the Rays with 56 starts at catcher this season, and he has caught 10 of 32 attempted basestealers (31.2 percent, up from 24 percent in 2015).
When Gamboa, 31, plays his first game, he will be the second-oldest player to make his Major League debut for the Rays, behind 35-year-old left-hander Jim Morris in 1999. Gamboa spent two days on the Orioles' active roster in April 2015, but he did not appear in a game.