Interest in Wi-Fi phones - long seen as bleeding-edge technology - has suddenly exploded, according to analysts.

The voice on Wi-Fi handset market went up by 76 percent in 2005, and will double to $200 million in 2006, predicts Infonetics Research. Dual-mode phones, that handle both Wi-Fi and cellular voice, are on an even more rapid growth curve, the company says.

By 2009, the voice on Wi-Fi market will be almost $1.9 billion, spreading out from the enterprise to consumers who will buy it as part of a broadband service bundle, the researchers predict.

"Organisations have extensive data networks that can potentially be used for telephony, eliminating the need for separate voice and data networks," said Richard Webb, wireless analyst at Infonetics. "Voice makes wireless LANs more desirable and mobility makes VoIP more valuable."

The number of handsets out there is increasing at an even faster rate than the market, since prices are falling as Wi-Fi phones sell in bigger volumes. The number of units sold doubled last year, and will go up by 158 percent this year.

Dual-mode handsets, almost unknown in these parts, make up a surprising amount of the world market - around a third In 2005, rising to 3/4 of the voice on Wi-Fi handset market by 2009. This is largely because of the Far East, where they have arrived first. The Far East makes up half of today's dual-mode revenue, with only 21 percent from Europe.