Buying digital music from a mobile phone is too difficult and the music and mobile phone industries need to improve the process to meet demand, the chairman and CEO of Warner Music Group Corp said on Wednesday.

A study last year found that only 8.5 per cent of people who own a phone that can be used to download and purchase music actually did so, said Warner chairman Edgar Bronfman Jr, speaking at the opening session of the 3GSM World Congress in Barcelona on Wednesday.

"Why? It's expensive, it's complicated and it's slow," he said. "It's amazing that we've generated as much revenue as we have given how cumbersome the experience can be."

Forty per cent of mobile phones in the UK have music players, said Ralph Simon, chairman of the Mobile Entertainment Forum for the Americas, speaking at the same event. This year, $9 billion in revenue is expected to be generated from mobile music, including ring tones and over-the-air downloads, Bronfman said.

While MTV's core customers are typically young and technically savvy, even they find buying mobile content too difficult, said Mika Salmi, president of global digital media for Viacom's MTV Networks. Simplifying the process is key, he said. For example, business models that make it easier for customers to pay for content could boost take-up, he said. MTV encourages operators that it works with to sell subscriptions, which it has found increases use because customers know exactly what they'll pay.

Buying a ring tone is an example of the complexity people can face. On average, users must click 20 times in a process that takes around two minutes to buy a ring tone, Bronfman said. Buying digital music on a phone is similarly complicated, he said.

"So many platforms aren't capable of even the most basic content configurations, like a track bundled with a video," Bronfman said. That means buying the same content that would typically be included in an album over a mobile phone would be comparable to having to visit three stores to buy the album, its liner notes and the art work, he said.

Apple's iPhone, the combined MP3 player and mobile phone expected to hit the market later this year, is a step in the right direction, Bronfman said.

"Before it's even hit the market it has raised the bar in terms of what users expect with a user interface and what music phones should do," he said. Now it's up to other mobile phone makers to meet users' expectations. "For those who invent with a similarly inspiring vision, the opportunity is immense," he said.