Mobile music remains a challenging business for Warner Music Group (NYSE: WMG), which reported today in its second quarter earnings ending March 31 that mobile remains “soft” as ringtone sales fell year over year in the US, and was flat massive 17.6 percent drop.

Two of the world’s leading music companies have partnered on a joint venture in China that will research and develop technology for distributing media to mobile phones.

The revelation Tuesday, sees Sony BMG Music Entertainment and the Warner Music Group join forces to invest in Access China Media Solutions, in what Warner dubbed “a strategic investment”.

Access – a joint venture between Japanese company, Access and US firm, Melodeo – creates software that makes the user’s experience of downloading music, video and ringtones, an easy experience. China currently has around 460 million mobile users and the pair are betting that as mobiles become more sophisticated, they will play an increasingly important role in entertainment.

Thomas Hesse, president of global digital business at Sony BMG said: “We think a good chunk of those consumers will be looking at their phones as an entertainment device.”

According to a press release from Sony and Warner, the pair will be focusing closely on Chinese oriented music.

Sony and Warner will also be keen to examine how to make China’s music market, which is rife with piracy, more secure. Michael Nash, senior vice president of digital and business development at Warner Music said: “Physical piracy in China is an enormous problem that’s created a crisis around investment in repertoire and artists.”