The move was first reported by ESPN NFL Insider Field Yates.
The 6-foot-2, 325-pound Siliga, who is more of a run-stuffing presence on the interior, injured his foot Sept. 21 against the Oakland Raiders. He was then placed on the IR/designated-to-return list Sept. 27.
The Patriots have good depth at defensive tackle with Vince Wilfork, Chris Jones, Alan Branch and Dominique Easley. Given that they had more time to have Siliga practice without counting against the active roster, the team potentially could have waited to bring him back and promoted a practice squad receiver or linebacker instead.
But bolstering the run defense with Siliga, a third-year pro out of Utah, trumped those possibilities.
The Patriots' open roster spot was created Thursday when receiver Aaron Dobson was placed on season-ending injured reserve.