I built a few of these at my last job. Much easier in the UK than the States.
The states *do* have premium SMS enabled now, but the rollout process is terrible at the moment. You pay 1k/month to reserve a shortcode across all the operators, or $500/month for a random shortcode. Then you have to get each operators approval to turn on the service for their network. (so you are probably going to be $3k into it before you get live on any networks)
Licensing content is a totally different beast. You need to pay royalties, and have approval from the artists (most artists give blanket approvals though). So, you need to report to ASCAP and another agency whos name I forget.
If you *dont* use premium SMS and charge via CC, it is simpler, and you can still deliver the ringtones using regular SMS messages.
If any of you are serious about launching a site, WireRunner.com has services and developers (including me) who have done all this stuff before. Drop me a line at
[email protected] !
Cheers.
Todd