Amp’d Mobile, a Los Angeles based company that operates its own mobile network offering entertainment content to young people, has raised $107 million more in a fifth round of capital, according to a regulatory filing cited by VentureWire (sub required).

Amp’d Mobile is a so-called “mobile virtual network operator,” because it does not license its own spectrum, but resells services using the network of other mobile phone operators. This is a tough market to play in, because branding is hard to create, given the dominance of established carriers. There are other a number of other players focused on the mobile market for young people, including Disney Mobile, Helio, and Virgin Mobile. However, Amp’d Mobile is reportedly showing strong growth in adoption and revenue.

According to VentureWire, hedge fund Old Lane Cayman Master Fund LP is the leading new investor. A dozen other backers have already pumped large amounts into the company. Its funding is now $350 million.

Past investors include Columbia Capital, Heights Capital Management, Highland Capital Partners, Qualcomm, Quilvest Ventures, Redpoint Ventures, Rho Ventures, TELUS Ventures, Tudor Investments, and Universal Music Group.