Vickerson started serving a four-game suspension for violating the NFL's steroid and related substances policy last week and will miss the final three games of the regular season before becoming eligible to return for the postseason.
Williams was the Titans' seventh-round draft pick out of Division II Washburn.
Tennessee also signed defensive tackle Derrick Jones of Grand Valley State to the practice squad. Jones was among five defensive linemen worked out Tuesday, including Steve Harris of Florida, Alex Morrow of USC, Jordan Reffett of Washington and Missouri's Lorenzo Williams.
