From personalised ringback music to mosquito-repelling tones, Asian telcos are getting creative in pursuit of download dollars. Korea's SK Telecom yesterday unveiled a service to turn the cellphone into a mobile mosquito repellent. For 3,000 won (£1.54), users can download a sound file that is inaudible to the human ear but helps ward off mosquitoes within a one-metre radius, the firm said. However, this "silent" melody consumes as much power a normal ringtone so customers will need to employ it sparingly. A small number of Asian mobile phone service providers are also offering personalised ringback tones. A ringback tone is what people dialling a telephone number hear between the time they finish entering the digits and when the call is answered. Many telephone service providers worldwide use the same, innocuous "ring, ring" sound to cover what would normally be silence. With personalised ringback tones, subscribers can replace "ring, ring" with a Shania Twain song, for example, or even a recorded personal greeting for their callers to hear. "Ringback tones add a new dimension of personalisation to the mobile communication experience," said Franky Lai, chairman of WiseSpot, one of a growing number of companies that supply the technology. Some carriers have added a muffled "ring, ring" sound to the track that's playing as a subtle reminder of what's going on. Replacing the familiar sound with a Paul McCartney song, for instance, could fool diallers into thinking they've been put on hold. Besides SK Telecom, two Chinese carriers have introduced similar services last week. SK Telecom had signed up about five million subscribers for ringback tone services at the end of 2002, with average spending per user of about $1.50 a month. The technology is going through the same metamorphosis as its cousin, the mobile-phone ring tone, which has been moving from conventional chirps to snippets of songs. Sales of ring tones have generated revenue for mobile phone carriers in Asia and Europe, and US sales of ring tones are beginning to pick up. Suppliers of ringback tones say that like ring tones, the technology gives carriers a way to differentiate themselves and bring in new sources of revenue. The market for mobile downloads is set to soar in Asia, helped by the region's growing cellular-penetration rates and the advent of multimedia handsets, says a market research firm. Downloading mobile frills such as ring tones, Java games and wallpapers has grown from an insignificant fad five years ago into a $1.3bn industry, telecommunications analysts Pyramid Research said in a report from news agency AFP. CNETAsia's staff contributed to this report.