Redknapp has regularly admitted he needs to bulk up his Blues squad before the transfer window closes after only bringing in David Stockdale, Marc Roberts and Cheikh Ndoye so far this summer.
Ryan Shotton is expected to join Middlesbrough by the weekend to further deplete Redknapp's options and the manager admits he is waiting to hear from other people working hard behind the scenes at St Andrew's to sign his targets.
Asked after Tuesday's 5-1 Carabao Cup win over Crawley about potential transfers, Redknapp said: "It’s down to other people. I don’t deal with that side of it. "I just pick them and rely on other people to get them in for me. So I am relying on other people to get them in. At the moment it’s taking a long time."
It's in defence where Redknapp is in greatest need, as he added: "We need a squad and at the moment we are short. I have got five defenders on my books and one of them is Robbo (Paul Robinson) who is 30-whatever. You can’t go through a season with five defenders.
"I have got three centre halves - it’s a small squad. We need to thicken it up and get some bodies in as quick as we can. But it’s not easy. Especially when you are looking for good players. Anyone can bring a load of rubbish in again. We are not going to do that."
Meanwhile, former Blues boss Gary Rowett has confirmed his old club have turned down an approach from him for striker Che Adams, who scored a hat-trick in the victory over Crawley.