IDC : Ringback tones to overtake ringtones in 2010

On the whole, mobile entertainment is expected to account for 5.1% out of a total of $800 billion (with a “b”) in global wireless service revenues that IDC is projecting by 2011. Downloadable ringback tones are already widely available on the Web from a variety of sources, including cellular carriers ranging from Verizon Wireless and Sprint to smaller regional carriers.
(via IDC)