Auction 73, the 700MHz spectrum sale, which kicked off in the US on Thursday, raked in over $2.8bn in bids within the first two rounds.

The much sought after C-block of spectrum drew an offer of $1.24bn, although the FCC has not revealed details of any of the bidders.

A total of 266 companies entered the auction, which is expected to last for around a month and has a total reserve of $10.4bn.

Among those companies expected to be spending big bucks are Google Airwaves, Alltel, AT&T, MetroPCS, Qualcomm, Verizon and investment company Vulcan Spectrum, which is headed up by Microsoft co-founder, Paul Allen.

Google has said that it is prepared to spend up to $4.6bn to secure itself a chunk of the spectrum. The web giant is one of the biggest backers of open access and is calling for more competition in the broadband space.

It is understood that at least one bid has also come in for the nationwide 10MHz D-block of spectrum, which is listed as significant item for the auction, but also has the most aggressive build out requirements of all the blocks. The winner of the D-block is required to build out a nationwide public safety network, which can also be shared with commercial carriers.

But mobile startup, Frontline Wireless, which had on its board former FCC chairman Reed Hundt, and was seen as the frontrunner for the public safety block, shut up shop a couple of weeks ago. The development raise concerns about whether any other company would bid for the D-block, but those fears seem to have been allayed for the time being at least.