He told the NFL Network in an interview with their "Total Access" show on Tuesday that negotiations with Porter for the number he previously wore for the Raiders "have stalled" but "we'll work on that in the upcoming days."
Woodson wore the No. 24 in his first eight seasons with the Raiders. When he left Oakland to sign with the Green Bay Packers in 2006 he switched to the No. 21.
If for some reason he can't get his trademark No. 24 before the season, he joked he might petition the league to take his no-number approach into the season.
"Well, I may have to petition to the league to see if I can just wear a blank jersey," he said in the interview.
Woodson practiced in a No. 2 jersey on Wednesday.
Woodson signed a one-year deal worth up to $4.3 million seven years after leaving Oakland as a free agent for Green Bay. Woodson got work at both strong and free safety in his first practice as the Raiders try to get him up to speed.
"It feels good to put the silver and black back on," Woodson said after practice Tuesday. "It's been a long time. I look good in silver and black, so it feels good to be back."
Coach Dennis Allen told reporters on Tuesday that while the Raiders are working Woodson in slowly, he doesn't "have any concerns that he'll be ready to roll."
Woodson also received strong interest from the Denver Broncos but told the NFL Network that their offer wasn't strong enough, even though their roster is far superior to that of the rebuilding Raiders.
"I came into the talks with Denver knowing exactly what I wanted," he said. "Even though I want to win a championship, I still want to make the business part of it right. Everybody talks to me as if they want me to come in and do all of these things but they don't want to treat me as a guy that is going to do all of those things.
"Those talks of course broke down, didn't happen and I left Denver and I got here to Oakland. & You can either take what they give you or you can say, 'Nah, I'll do something different,' and that's the way it went," he said.
Woodson, 36, is an eight-time Pro Bowler and was the 2009 NFL Defensive Player of the Year. He has 55 career interceptions, 17 sacks, 24 forced fumbles and 11 interception returns for touchdowns in eight seasons in Oakland and seven in Green Bay.
He played just seven games last year because of a broken collarbone but brings leadership and playmaking ability to a rebuilding defense that was lacking both.
"He's a legend," linebacker Nick Roach said. "He's a living legend that is still playing, still playing at a high level. I played against him many a time when I was back in Chicago. I think it's going to be great for the locker room just having that experience and having that knowledge."
Information from The Associated Press was used in this report.