Clubs can sign free agents outside of transfer windows but Chris Coleman has confirmed nobody else will be arriving at Sunderland.
The Black Cats added Kazenga LuaLua, Jake Clarke-Salter, Ovie Ejaria, Ashley Fletcher and Lee Camp to the squad in January with Chris Coleman declaring he was happy with the business done.
Liverpool loanee Ejaria, Fletcher and Camp all made their debuts in the 2-0 defeat to Ipswich Town at the Stadium of Light and Coleman said only the current squad can turn the situation around.
After 30 games, Sunderland are second bottom, two points from safety.
Coleman, who confirmed nobody else would be coming in, added: "We are where we are. The new boys, Fletcher will get better when he gets more minutes, Ovie did a lot of good things, he will find the pace of the Championship.
"Kaz needs fitness. I am happy with the faces we have got in, the worry for us is when we go a goal behind we don't come back.
"I think we've done it once in two years, I'm told, here. That is a worry because you won't always go 1-0 up.
"There is only us that can change it, only us that can change the results. Nobody else is coming in. We have what we have got."
Sunderland were denied a penalty with 25 minutes to go, sub George Honeyman crossed the ball and it hit the arm of Ipswich Town defender Jonas Knudsen.
Referee Darren England waved away the strong Sunderland appeals, with Coleman among them.
He added: "25 minutes to go it has to be a penalty, it has to be.
"I'm not saying that because we lost the game, just give the decision. It is handball. He is 10 or 15 yards away, it is a penalty.
"Whether we score or not, it is a penalty. It is hard graft, hard going.
"The second goal two games running a minute before half-time is a tough one to swallow."