Unga, 27, is a former seventh-round pick of the Bears during the 2010 Supplemental Draft. He spent the first three years of his NFL career with Chicago, but has found limited interest as a free agent on the open market this year.
Booth, 23, signed with the Bears as an undrafted free agent out of Temple, but lasted just a few months with the team before he was placed on waivers after Chicago signed OT Dennis Roland.
Hall, 28, signed with the Jaguars a little over a week ago. He has spent time with the Eagles, 49ers and Chiefs since entering the NFL as an undrafted free agent out of the Air Force Academy back in 2008.
Hall appeared in eight games for the Chiefs last season, catching two passes for 20 yards receiving and playing a total of 43 snaps. He also contributed on special teams for Kansas City.
Ewing, a 2012 fifth-round pick, was claimed off of waivers from the Falcons back in March. He appeared in two games last season, catching two passes for 29 yards, before being placed on injured reserve with a separated shoulder.