Despite the fact that over 87,000 of the devices have been sold in the UK since their launch in 2003 in the US, using one in the UK is illegal.
Their use is banned as an unlicensed radio transmitter under the Wireless Telegraphy Act (WTA) 1949, legislation originally drawn up to control public broadcasting.
The iTrip device plugs into an iPod and allows users to tune into a frequency which can be received by a car radio or home stereo.
The Wireless Telegraphy Act is in the processing of being amended and will be enacted next month, making the iTrip legal to use in the UK.
Some shops in the UK already openly sell the iTrip for use in countries where similar laws have been amended or were never applied.
The device has CE approval for sale in European Union countries, and some, such as Germany, have already amended their equivalent of the WTA.
"The iTrip is the number one best selling iPod accessory in the US," said Steve Hawkins, managing director of AM Micro. He estimates the immediate market in the UK to be in excess of two million people.
The iTrip standard version, which fits all iPod models after generation 3, carries a suggested retail price of £29. An iRoadtrip model which includes a charger and car cradle is £49.
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