More information about the bidders in the upcoming auction for 700 MHz spectrum has trickled out, as people figure out who’s behind the different registered bidders (PDFs of all 266 entities are here and here). It wasn’t clear earlier if EchoStar (NSDQ: DISH) had registered; it has done so through an entity called Frontier Wireless, reports Tech Trader Daily. Large companies and deep-pocketed investors often participate in the auction through separate entities or under different names, both to try to maintain some anonymity and to secure discounts and other benefits the FCC extends to certain small companies and other “designated entities”.

The WSJ reports that Mexican telecom billionaire Carlos Slim Helu is backing one of the companies that’s registered to bid, as has money manager Mario Gabelli. Gabelli’s participation is noteworthy, if only because Gabelli had been accused of fraudently taking advantage of the designated-entity discounts in spectrum auctions in the 1990s; he settled the civil suit with the government in 2006, paying $130 million but not admitting any wrongdoing.

Many of these registered bidders will drop out when it comes time to deposit earnest money with the FCC, before the auction begins. The number left standing after that should thin out pretty quickly once the auction gets started, as the 700 MHz spectrum on offer is too valuable—and potentially lucrative—to allow for any bargains. At the very least, one of the nationwide licenses should go for $4.6 billion, as that’s the bid needed to put the open-access rules on the C-block license into place. Google (NSDQ: GOOG) has said it’s prepared to bid that much for the license, even if it doesn’t intend to win the auction and buy the license itself.