By eliminating most of the technical challenges and big expenses and risks, Sonopia has significantly lowered the barriers. Creating an MVNO is as simple as going to Sonopia's website, creating a profile, choosing which of Sonopia's phones and calling plans to offer members, uploading designs for customized splash screens and Web pages, creating specialized content, and then inviting potential members to join. "We enable anyone with an idea to express to create a mobile carrier in a matter of minutes," says Christensen.

Sonopia handles details such as shipping phones to customers and processing bills and payments, but every interaction with customers occurs via the MVNO's own brand, not Sonopia's. Sonopia keeps the lion's share of subscription fees--it's the one, after all, providing the expensive technological back end--but it gives each MVNO three to eight percent of the revenue from cell-phone payments. And members who buy their phones through Sonopia MVNOs get access to a large catalog of programs that run on BREW, a common platform for mobile software applications.

Christensen says the biggest challenge in building Sonopia's service was not building the phone-networking infrastructure, but creating simple Web-based interfaces that nonexperts could use to create, brand, and customize their networks. "We spent a lot of time distilling the sign-up process into as few steps as possible," says Christensen. "And building tools that enable the common man, as opposed to a programmer, to create content that is going to appear on many models of mobile phones was a major design hurdle."

As part of Sonopia's service, customers can join interest-based social networks consisting of people across many Sonopia-powered networks, and operators can send daily news blurbs, blog entries, and alerts to their members' cell-phone screens.

If the idea behind Sonopia catches on, it could help undermine the highly centralized structure of today's wireless industry, ultimately increasing the variety of content and applications available on mobile phones. The essence of Sonopia's business, says Christensen, is to help operators tailor their services to their members' interests and needs. "To make the economies of scale work, the big carriers have to find a common denominator and try to make as many customers as possible happy as much of the time as possible," he says. "We have turned that model upside down. For us, the smaller the network, the better. Even if there were millions of Sonopias, each with only one subscriber, we would still be profitable because we've built our system to have a very low incremental cost per new Sonopia."