The report came from Fox Television's Jay Glazer, who didn't name his source and said the league isn't commenting.
Earlier this month, sports website DeadSpin.com said Favre invited Sterger to his hotel via those voicemails when both were with the New York Jets.
Jenn Sterger Said to Hire Lawyer
Will Favre's Marketability Be Sacked by Scandal?
"I'm going back to the hotel and just, just chill. … Love to have you come over tonight," one voicemail said.
Deadspin also reported that lewd, below-the-waste photos were sent to Sterger from the same phone as the voicemails.
Favre, who is married with two children, reportedly denied sending those photos.
Sterger's legal team is whether to talk to the NFL.
At issue? "What the parameters would be. Where would it be? Who would she talk to? What would be the questions?" says CBS Sports analyst Charley Casserly.
If Sterger decides not to cooperate, there would likely be no discipline for Favre, Glor says.
Of course, there's
Favre makes an estimated $7 million to $9 million dollars a year on endorsements.
And this past weekend, "Saturday Night Live" took a shot at his ads for Wrangler jeans, particularly one in which he says he loves the open-fly types.
There are reports that Favre and Sterger are negotiating a cash settlement.
But Casserly says - not according to what he's heard. He tells CBS News, "There have been absolutely no discussions about any matter with anybody from Brett Favre's camp."
On the field, Favre wasn't at his best Sunday night. In a
After the game, he didn't talk about the scandal.
Now the question is -- will Jenn Sterger?
If she does cooperate with the NFL, Favre could face disciplinary action -- a fine or suspension. But first, the league would probably have to prove he did in fact send those lewd photos, Glor says, and that could prove difficult.
Sunday night's was Favre's 290th consecutive game -- by far the longest streak in NFL history. If the league finds that he is behind those photos, that streak could wind up being broken -- by suspension, Glor points out.