Here's a paper on it: http://www.cramton.umd.edu/papers2000-2004/00jre-collusive-bidding-lessons.pdf http://www.cramton.umd.edu/papers2000-2004/00jre-collusive-

Here's a paper on it: http://www.cramton.umd.edu/papers2000-2004/00jre-collusive-bidding-lessons.pdf http://www.cramton.umd.edu/papers2000-2004/00jre-collusive-b... Here's an FCC write-up of one of the more egregious cases, where the participant was fined $650k https://wireless.fcc.gov/auctions/anticollusion/releases/FCC-98-203.pdf https://wireless.fcc.gov/auctions/anticollusion/releases/FCC... To answer your question, I believe they weren't allowed to communicate.