The 31-year-old Walter signed with the Texans in March 2006 after playing his first three NFL seasons in Cincinnati. He caught 326 passes for 4,093 yards in his seven seasons with the Texans. Walter made 41 catches for 518 yards and two touchdowns and was the Texans' third-leading receiver in 2012.
Walter was due to make $2 million in base salary in 2013 and he never became the deep threat the Texans wanted to complement Andre Johnson. The move leaves the Texans with three much younger receivers on the roster to fill out the depth chart behind Johnson -- Keshawn Martin, Lestar Jean and DeVier Posey.
Later Tuesday, Philadelphia signed the versatile Casey, one of the Texans' unrestricted free agents.
Several teams reportedly lined up to court Casey, who had his best statistical season in 2012, setting career highs in receptions (34) and yards receiving (330). A fifth-round pick out of Rice in 2009, Casey began his career at tight end, then moved to fullback in 2011, after Vonta Leach signed with Baltimore.
Quin was a fourth-round pick in 2009 and played cornerback for two seasons before moving to safety in 2011. He made 107 tackles, including his first career sack, and intercepted two passes in 2012. He's started 60 consecutive games and intercepted five passes for the Texans.
Barwin's numbers dipped after he led the Texans with 11 1/2 sacks in 2011. He had only three sacks, but deflected five passes in 16 starts in 2012. Barwin moved to outside linebacker in 2011 after missing most of the 2010 season with a broken right ankle.
McCain, 26, missed the final four regular-season games and the playoffs with a broken left foot. He had surgery on Dec. 3 and the recovery was expected to take about eight weeks. McCain was a sixth-round pick by Houston in 2009. He broke up 26 passes and had four interceptions in his four seasons.
Cody missed three games last season with back soreness, and he had surgery to fix a herniated disk in February. Cody who played at Southern Cal, was drafted in the second round in 2005 by Detroit and signed with the Texans as a free agent in 2009.
Earl Mitchell proved to be a capable backup to Cody, making 51 tackles, deflecting three passes and forcing a fumble in 2012.
Dobbins signed with the Texans as a free agent in August 2011. He stepped into a starting role in 2012 after Brian Cushing tore his left anterior cruciate ligament against the New York Jets on Oct. 8. Dobbins made 43 tackles and recovered four fumbles in 14 games last season. He was also Houston's special-teams captain.