Japanese mobile phone companies are hoping to equip children as young as five with their own phones, because almost all other potential customers already own a handset, according to recent research.

"Future growth in the Japanese mobile market will be centred on the under 14s and over 55s as 100 per cent penetration is reached in all other age groups," said research group the Wireless World Forum in a report published last week. 

Most of Japan's mobile operators reported improved revenues in 2005, but this was because they attracted new subscribers, not because they generated more money from existing customers.

The percentage of phone-toting five to nine year olds in Japan will more than double from 29 per cent to 64 per cent by 2007, according to the report.

Revenues from mobile games and music, most popular with younger customers, will grow in tandem with the burgeoning youth market.

In the short term, however, the fastest growing new market segment will be at the opposite end of the age spectrum: 55 to 65 year-olds, 1.62 million of whom are predicted to pick up their first handset this year.