Frontline Wireless, a startup that had planned to bid in the U.S. Federal Communications Commission's upcoming 700MHz spectrum auction, has "closed for business," a spokeswoman said Wednesday.

Frontline, backed by veterans of the wireless industry and U.S. government, was one of the major advocates of a plan for the FCC to pair about 10MHz of spectrum set aside for emergency response agency communications to another 10MHz to be sold in the auction starting Jan. 24. The auction winner would then be required to build a wireless network that emergency responders such as police and fire departments could share with commercial interests.

Frontline had also pushed the FCC to adopt so-called open-access rules on part of the 62MHz of spectrum to be auctioned.

The FCC in July largely adopted the emergency communications auction plan advocated by Frontline and other groups, and it approved an amended open-access plan on 22MHz of the spectrum. The FCC required that the winner of the 22MHz segment allow any wireless devices to connect to the network, meaning wireless telephone customers could bring their handset devices from other carriers. The FCC also prohibited the winning bidder on the 22MHz chunk of spectrum from blocking or slowing wireless and Web content from competitors.

Frontline spokeswoman Mary Greczyn said Wednesday the company would have no further comment beyond saying Frontline is "closed for business at this time."

Up-front payments for bidding in the 700MHz auction were due Jan. 4. The up-front payment for the D block, the spectrum for emergency communications, was $128.2 million, and the payment for the 22MHz C block was $282.1 million.

Frontline, based in Greensboro, N.C., first made a splash in early 2007 when it proposed an open-access network that emergency responders would share with commercial providers. Frontline said then it planned to offer wholesale access to the network to other wireless providers.

Frontline was backed by several heavy hitters in the wireless and tech industries, as well as former senior U.S. government officials. Haynes Griffin, founding CEO and president of Vanguard Cellular Systems, served as Frontline's CEO, and Janice Obuchowski, former head of the U.S. National Telecommunications and Information Administration, served as the company's chairwoman. Reed Hundt, a former chairman of the FCC, served as Frontline's vice chairman.

James Barksdale, former CEO at Netscape, and John Doerr, a partner in the Kleiner Perkins Caulfield & Byers venture capital firm, were among the company's backers.