The 33-year-old insists that he never told the 49ers that he was retiring and believes that the confusion was born out of miscommunication.
"No, no. It's just miscommunication between me and Harbaugh. We talked about it. I called him to communicate that to him. It was just pretty much miscommunication between me and him," Wallace told reporters.
The former Seattle Seahawks quarterback will act as cover for Aaron Rodgers and plans to use his experience to help him if he is called upon.
"I just have to lean on my experience and I'm pretty sure if something was to happen, God forbid, that we would try to lean on some of the stuff that I learned in the past, just to try to get through it," Wallace added.
"But we're not going to talk about that. We want the man to stay upright and continue to keep doing his thing."
The Packers are the third team that Wallace has joined during the off-season, having also spent brief stints at the New Orleans Saints and the 49ers.