Roughly 12 billion text messages are sent every month by users worldwide to PCs, personal digital ssistants and mobile phones, with another three billion sent by pagers, according to researcher Gartner.

Standard messaging functions are also being transformed into instant messaging (IM) services, which are more collaborative, offering features such as 'buddy lists', said the company.

While traditional management protocol suggests that IM should be banned in meetings, Gartner analysts see productivity benefits online and offline with what it described as the electronic equivalent of students passing secret notes around during class.

Analyst Ken Dulaney said: "With 15 billion messages flying through our hands each month, that PowerPoint slide in the live meeting better be relevant and compelling, otherwise, workers will dive into more productive interactions via wireless IM."

Separately, Gartner also reported worldwide mobile phone sales figures for 2000, which saw Nokia consolidating its position as the number one vendor with shipments making a 66 per cent leap.

Manufacturers shipped a total of 412.7 million handsets last year, an increase of 45.5 per cent over 1999. Nokia, Motorola, Ericsson, Siemens and Panasonic made up the top five vendors in market growth shipments for the year, said Gartner.

But the researcher noted that the industry was affected by lowered barriers to entry that allowed an influx of smaller manufacturers to exploit demand in some of the Far Eastern markets, such as China. Also, Wap failed to impress mobile users around the world, according to Gartner.

"Persistent rumours of a market slowdown that dogged the industry throughout the year started to prove true toward the end of 2000," said Bryan Prohm, an analyst at Gartner's telecommunications group. "There is significant stock carry-over to the beginning of 2001, meaning the number of total shipments in 2000 was about six million units lower than previous estimates."