Look, Ma--No Towers

"I'm very convinced that had we not elected to go with Telcordia, we would not have made that launch on time," Parks says.

The potential risks involved in becoming a virtual cellular system operator likely won't scare off would-be mobile network providers. Virgin Mobile was Telcordia's first customer for the virtual system technology, but the vendor says several other companies have expressed interest in using its software to launch virtual mobile networks.

There's a reason for the momentum. In Europe, regulations have forced some telecommunications providers to abandon their cellular ventures, so several providers have launched virtual networks to continue to offer bundled landline and mobile services. In this country, AT&T may launch a virtual network to keep its AT&T Wireless brand alive after its existing wireless service is absorbed by Cingular, which disclosed in February that it would acquire that business.

Other big brands seem poised to follow. In February, at the Walt Disney annual shareholder meeting, Walt Disney Internet Group president Steve Wadsworth suggested that one potential area of expansion for the company is to offer branded cell-phone services from its Disney and ESPN units, including mobile access to sports scores, video highlights, and fantasy sports games, all bundled into one package.

But such a move isn't risk free. While cheaper than obtaining wireless-broadcasting licenses and installing cell towers around the country, the virtual approach still requires a substantial investment of money and effort. Still, by breaking into the top 10 in 18 months, Virgin Mobile has shown that it's an effective way to compete against rivals that spent billions of dollars to build cellular networks. And Virgin Mobile's success raises an interesting question: Who's next?