According to a report by M-Metrics, the rise in music-phones has spurred adoption of mobile music consumption across the United States and Western Europe, but the firm reports that sideloading accounts for 83% of mobile music usage across France, Germany, Italy, Spain, the UK and the United States.

The research firm found that with the exceptions of Spain and the United States, more mobile music consumers listened to music that was shared (for example, between phones via Bluetooth) than was downloaded directly to the phone using a music service. France and the UK posted the highest frequency of this activity, accounting for 12.5% of those who listened to mobile music in the month. At the other end of the spectrum was Spain, with only 7.1% of mobile music users transferring music between devices.

“Mobile music is quickly catching on, and the fact that consumers are sharing music demonstrates its potential as a social, viral phenomenon centered on mobile handsets,” said Jen Wu, M:Metrics analyst, in a statement. “The proliferation of music phones is causing a shift in digital music toward the mobile platform, which opens numerous opportunities for music-related content, services, hardware and accessories built to accommodate or enhance these mobile music activities.”

The firm also found that 10.7% of mobile subscribers across the six geographies reported listening to music on their mobile devices, ranging from 5.7% in the United States to 20% in Spain.

Music handset penetration has grown considerably in the United States and Western Europe, at an aggregated rate of 50.7% growth from November 2006 to November 2007 across the six geographies. The United States has the fastest-growing market, with 63.6% growth, from 23.2 million subscribers owning music phones in November 2006 to 63.8 million one year later.