The U.S. appetite for ringtones has not developed as quickly as in other markets, and no company has emerged to do for ringtones what Apple has done for digital downloads with its iTunes/iPod campaign.

A big part of the responsibility for building the market falls to the five major U.S. carriers — Verizon, Sprint, Cingular/AT&T Wireless, T-Mobile and Nextel — which control the pipeline to their customers.

However, it is generally held that mobile music promotions are more effective when some combination of the carriers, handset manufacturers, ringtone aggregators (like Infospace Mobile, Zingy and Faith West) and record labels co-market their products.

Perhaps the most aggressive U.S. mobile music marketer has been Virgin Mobile — a mobile virtual network operator (MVNO) that leases Sprint’s network infrastructure and sells minutes to customers.

In June, Virgin Mobile launched its “First Dibs” partnership with Universal Music Group, offering exclusive master ringtones from Shady/Interscope act D12. A second round has exclusives from G-Unit artists Lloyd Banks and Young Buck.

A source says Virgin Mobile spends about $50 million annually on advertising. Much of that is used to target the music-intensive youth market with ads in Rolling Stone, Spin and Blender and on MTV and MTV2, as well as sponsorship of the recent MTV Video Music Awards.

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