InPhonic, the wireless phone and service provider which held the top spot in the 2004 Inc. 500 list of the nation's fastest-growing private companies, has filed for Chapter 11 protection after agreeing to sell its assets to a private-equity firm, the company said in a statement.

In 2003, the company grossed $119.4 million, marking a three-year growth rate of 23,833 percent. Now, the company expects that shares of its stock, which is listed on the Nasdaq, will have no value.

"We intend to use this filing to take the actions necessary to position InPhonic for future success," Andy Zeinfeld, the company's CEO, said in the statement. "We want to assure our customers, our employees and our partners that InPhonic is operating business as usual during this transition."

In October, Zeinfeld took over for founder and former CEO David Steinberg, who is still chairman of the company's board of directors.

The sale, to an affiliate of Versa Capital Management of Philadelphia, is expected to close before the end of the year.