A new chart is being launched to reflect the increasing popularity of musical mobile phone ringtones.
Ringtones are so popular they now have their own official chart
The fortnightly chart will count down the 20 most popular tones downloaded onto mobile phones and will be published in Music Week magazine.
Most current pop hits are available to buy as mobile phone rings for between £1.50 and £3.50.
The chart is compiled by accountancy firm KPMG, using information supplied by mobile phone companies.
"We are compiling the report based on sales data
from the mobile companies that supply the contents that people download onto their phones," said a spokesman for the company.
An estimated £70m of ringtones were sold in 2003 - up from £40m in 2002 - according to the Mobile Data Association (MDA), a non-profit trade group.
However, contrary to reports, the market for ringtones is not expected to overtake CD singles for some time yet.
According to mobile content provider ringtones.co.uk, the best-selling musical ringtone at present is I Don't Want You Back, the former number one single by US singer Eamon.
Nokia's website, however, puts Britney Spears' single Everytime at number one.
The best-selling ringtone of 2003 was Beyonce's song Crazy in Love, according to ringtones.co.uk.