Short-lived mobile virtual network operator (MVNO) Amp'd Mobile Inc. is likely to shut its doors by the end of the month, according to a post on the firm's Website.

The two-year old operator has updated a statement on its Website to say that it is "potentially suspending U.S. operations on July 31st." Amp'd originally said it was shutting up shop this week. It claims that another carrier could buy its assets, saying that it is in talks with "several interested parties."

Amp'd had filed for Chapter 11 bankruptcy protection early in June, following revelations that many of its young customers hadn't been paying their bills, and that the firm owed its network operator, Verizon Wireless , millions of dolllars. (See Amp'd Crank'd.)

Even as it filed for Chapter 11, however, the Los Angeles-based MVNO was saying it would be able to return "stronger than ever" by working with a large investor to "obtain debtor-in-possession financing."

Apparently, this funding lifeline hasn't come through yet. Amp'd hasn't returned calls or emails on the matter.

Amp'd amply illustrates one of the two extremes in the U.S. virtual mobile operator market. Firms such as Amp'd have spent big and flamed out in short space of time. On the other hand, Virgin Mobile USA Inc. (NYSE: VM) has also built up debts but is plotting a $506 million IPO. (See Virgin Guns for $506M US IPO.)— Dan Jones, Site Editor, Unstrung