Leyton Orient remain keen on Birmingham's Oji
The 22-year-old defender, who made just four appearances for the Os, has returned to parent club Birmingham after spending a maximum 93 days on loan at Brisbane Road.
But Ling has refused to rule out a move for the player in the New Year.
He said: "I'd like to thank Sam for his efforts during his time here because, although he may not have got as much pitch time as he would have liked, he has been an important part of the squad.
"His attitude has been first class and he did well whenever he was called into the side.
"The rules state that he must go back to Birmingham now, but we will look at the situation again when the January transfer window opens."