The FCC is moving to speed up the bidding process in its auction of 700 MHz spectrum, and the auction could be concluded in days. Total bidding for all licenses was $18.9 billion on Wednesday.

Under Phase 2 of the auction, new bids only have to be 2% higher than the current bid, rather than the 5% increase required in earlier rounds of bidding.

Most interest has focused on the C-Block, which carries a stipulation that the winning licensee be required to create an open segment in the spectrum for interchangeable devices and services for consumers.

While speculation about the identities of the bidders, which bid in secret, has ranged far and wide, most observers believe Google and Verizon Wireless are among those seeking the C-Block. Speculation suggests that Verizon placed the most recent bid of $4.74 billion. The previous bid of $4.71 billion -- likely placed by Google -- had met the minimum price the FCC had set for the package of licenses.

AT&T, which is the largest U.S. mobile phone provider, already has plenty of 700 MHz licenses through its $2.5 billion purchase of spectrum, which was made before the start of the auction. AT&T has likely been fleshing out that spectrum block with purchases of B-Block licenses in the auction. Earlier this week, the FCC approved AT&T's pre-auction purchase of licenses.

The third and fourth largest cell phone providers -- Sprint Nextel and T-Mobile -- are believed to not be participating in the auction; Sprint is racked with management upheaval and is considering a massive write-off involving its acquisition of Nextel, while T-Mobile picked up wide swathes of spectrum in another recent FCC auction.

Bidding for the D-Block -- with combo commercial-public safety capabilities -- has stalled for days at $472 million, well below the $1.3 billion reserve set by the FCC. The block is likely to be reauctioned with a new set of guidelines. While bidding for nearly 1,100 licenses scattered about the country is continuing, competition has slowed to a crawl.