MVNOs have become popular in the past year, as big brands develop new mobile services to target narrow market segments that the larger mobile phone carriers aren't reaching. For example, Disney Mobile is going after families; ESPN is targeting the young sports-watching male; while Virgin Mobile has focused on the teenage audience that shops in its music stores.

To differentiate its mobile service from what's already available from the big carriers, Helio has focused on providing easy access to mobile Internet content such as game, music and video. Earlier this year, it announced deals with MySpace.com and Yahoo.

"Helio isn't for everyone," Dayton said. "It's a service that has been custom-built for the lifestyle of young people who have their mobile device at the center of their universe."

The company has also developed several of its own features, including something it calls Helio on Top, or HOT, which allows subscribers to program live content feeds to be sent directly to their Helio device's idle screen. Subscribers can select from 10 different live channels, including CNN, Fox Sports, MTV News, MySpace, Surfline and Yahoo.

Helio has also developed new features called "gifting" and "begging" that make it easier for customers to share purchased mobile content among friends. Gifting lets people purchase a music video, game or piece of content directly from their handset and have it delivered, over the air, to another Helio subscriber's device. Begging does the opposite by allowing users to "beg" another Helio subscriber to purchase content for them.

Last month, the company unveiled the two phones that will be used for the service: the Hero, which costs $275 and the Kickflip, which sells for $250. Each device features 2.2-inch, color LCD displays, removable memory, and a 2-megapixel camera with digital zoom and flash for capturing pictures and video. The Hero also comes with stereo speakers. Because Helio's subscribers are likely to view their phones as accessories, they can also sync their address books over the air to another Helio phone.

"Just as people have different shoes or handbags that they wear at different times, they'll also use different phones," Dayton said. "We're getting to the point where cell phones are more than communication tools; they're accessories, too."

Dayton also claims Helio's pricing is unique, because it's not "nickel and diming" consumers, forcing them to pay separately for mobile Internet or text messaging services. Helio's All-In Membership includes unlimited night time and weekend voice calling, voice and video messaging, mobile Internet surfing, such as MySpace browsing and Yahoo searches, or access to the 3G network to download content for a fixed rate. The service has three tiers of pricing based on minutes used: 1,000 anytime minutes costs $85 per month; 1,500 anytime minutes costs $100 per month; and 2,500 anytime minutes costs $135 per month. Helio games are priced at a flat rate of $5.99 to buy, or subscribers can opt to trial games by renting a game for a week for 99 cents.

Starting Tuesday, Helio phones and service will be available online, or by calling 888-88-HELIO. By the end of May phones will be in nearly 1,000 retail locations, and in 3,000 by the end of the year. Helio's distribution partners include leading national and regional retail chains such as Fry's Electronics and Tower Records. Helio will also be available at more than 100 college and university campus bookstores across the nation.