The deal with Ross, who spent the past four seasons with the Atlanta Braves, is pending a physical, the official said Monday. The official requested anonymity because the contract has not been announced.
The agreement was reported first by FoxSports.com.
Ross, a strong defensive catcher, played eight games for the Red Sox late in 2008, going 1 for 8, after being claimed off waivers following his release by the Cincinnati Reds.
The 11-year veteran batted .269 with 24 homers and 94 RBIs in 227 games with the Braves. Last season he hit .256 with nine homers and 23 RBIs in 62 games. For his career, Ross is batting .238 with 84 homers and 248 RBIs in 658 games. He posted career highs of 21 homers and 52 RBIs in 2006 when he batted .255 in 90 games.
Saltalamacchia batted .222 with 25 homers, 59 RBIs and 139 strikeouts in 121 games last season. Lavarnway, who joined the team on Aug. 1 when he was called up from Triple-A Pawtucket, hit .157 with two homers and 12 RBIs in 46 games.