Ring Ring Costs Bling Bling

Use a ring tone, take a license! Here's hoping the best outcome is an upsurge of original composition ring tones (for which no license would be required). DIY Ringtone.
The Registrar of Copyrights was pursuaded by the Recording Industry that ringtones qualify as protectible subject matter (digital phonorecord deliveries, DPD) as defined by US Code. Chapter 17, section 115.
Next step is determining a royalty rate for ringtones that are "mere excerpts" and not "derivative works."
Copyright owners asserted that the statutory license for making and distributing phonorecords of musical works is narrow in scope and does not encompass ringtones, which involve only a portion of the underlying composition and are not representative of the entire musical work.
But a portion is enough, according to the Registrar for Copyrights, MaryBeth Peters.

While sharing the point of view of the RIAA (Recording Industry Association of America) , Peters included examples of instances in which the ringtone is not subject to Section 115. Ringtones that are mere excerpts of a pre-existing sound recording fall squarely within the scope of the statutory license. However, those that contain additional material “may actually be considered original derivative works and therefore” are not subject to royalty payments.

In the Matter of Mechanical and Digital Phonorecord Delivery Rate Adjustment Proceeding, No. RF 2006-1, Cpy. Off.).