In hip-hop parlance, 28-year-old Alexander Amosu is what you'd call a “playa.” In the business world, he's known as a success story. A self-made millionaire, Amosu is a magazine journalist, a nightclub DJ and the host of his own U.K. TV talk show,“Rich N Famous.” Oh, and he also started his own ringtone company.

Four years ago, Amosu discovered that his new Nokia phone allowed him to compose custom ringtones. He spent a few hours perfecting a ringtone version of Jay-Z's hip-hop hit “Big Pimpin',” which was absent from mainstream pop menus of ringtone vendors at the time. After hearing the final product, his 21-year-old brother begged Amosu to share it, which he did. Within hours, Amosu was flooded with phone calls from his brother's friends who just had to have it, too. After the second request, he started charging them £1 each.

Today Amosu's company, RnB Ringtones, boasts 2 million customers across Europe and attributes its success largely to its tight integration with youth culture. But as rivals saturated the hip-hop market, RnB staked out other niches, including Bollywood and Hebrew music and Yoruba, the music of Amosu's Nigerian heritage.

“We flipped the script and started being multi-cultural,” he said. Competitors may have 50 Cent's latest rap single, but do they have “Ishq Da Maara Hua,” by Sssshhh?

Still, not much untraveled ground is left in the U.K. ringtone market, so after selling most of his stake in RnB, Amosu founded MobsVideo, which offers free music and sports videos to kids who agree to watch one “advert” a month on their phones. Most recently, he's been meeting with American wireless operators to plan an RnB/MobsVideo invasion of the states, setting up ringtone services on the fly for blue-chip companies.

“I know exactly what to do to make it a success story overnight,” Amosu said. For those blue-chip American companies, it means, “You want to partner with a success story.”