A call to relax the law on making workplaces pay a licence fee for playing music has been made by the Federation of Small Businesses (FSB).
Having a radio on or playing music to customers on hold incurs a fee to the Performing Right Society (PRS), which collects money on behalf of musicians.
The FSB said the law was unfair on small businesses and was too expensive.
But the PRS defended the fee, saying said studies "have shown" music at work "improves productivity performance".
It is estimated that more than half a million businesses across the UK are playing music illegally.
Out of the blue our members are being harassed by the PRS
Stephen Alambritis from the Federation of Small Businesses
Stephen Alambritis from the FSB told BBC Radio 4's Today programme he was concerned that many businesses had not heard of the Copyright, Designs and Patents Act 1988.
It states that if copyright music is played in public, every writer or composer must give permission, and anyone without a licence faces the possibility of court and legal costs.
Businesses must pay for playing music, regardless of whether staff or customers can hear it. They can claim a reduction for a small portable radio or television set but a charge does still apply.
"Out of the blue our members are being harassed by the PRS," Mr Alambritis said.
"We have no problem with the PRS collecting money from restaurants, cafes, pubs and bars and those tunes on mobile phones in call centres."
It is important to recognise the value that music adds to business
Adrian Crookes, director of communications at the Performing Rights Society
He told the BBC he was concerned that a fee was still expected when "the radio is essentially in a backroom for the boss, not intended for the staff but the staff may be within earshot - or there may be some customers within earshot".
He added one member had been who was contacted "eight times in 10 days" by the PRS and said the fee was complex for businesses to administer.
Adrian Crookes, director of communications at the PRS, defended the licence, saying his organisation was not "harassing" small businesses.
"I think it's important to remember that the 60,000 songwriters and composers who are our members are small businesses themselves, so we're very, very sensitive to the pressures on small business," he told Today.
"And we wouldn't choose, for example, sole traders or people working in their home."
Payments to musicians
He said licences were "very reasonable", adding: "Our smallest licence starts at £66 a year, which is a little over £1 a week."
Last year the PRS made £134m from Public Performance Licences, keeping 6-12% before passing the royalty fee on to the artist. The songwriter can make anything between £1 and upwards of £20 per play.
Mr Crookes said that workplaces should pay for the "business benefit" of playing music.
"There are studies that have shown that it improves productivity performance, raises morale, team-building," he said.
"It is important to recognise the value that music adds to business and ensure that songwriters and composers who've made that contribution are fairly paid."
He said the PRS tried to make the licence "fair" by charging businesses according to their size, square meterage and number of employees.
Payments to musicians were "small amounts of money", he said, adding that "90% of our members are earning less than £5,000 a year from royalties".
"So the work that we do in collecting their royalties for them is vital to keep them creating more music which in turn helps business atmospheres."
• About 90% of youngsters aged between 14 and 23 own an MP3 player containing an average of 1,770 tracks - half of which have not been paid for, a survey has suggested.
The research was based on 773 respondents and carried out in February and March 2008 by the University of Hertfordshire.
It found that 58% of respondents had copied music from a friend's hard drive to their own, and 95% copy music in some way. Money spent on live music exceeded that spent on recorded music.
Feargal Sharkey, chief executive of British Music Rights, which commissioned the survey, said: "The music industry should draw great optimism from this groundbreaking survey.
"First and foremost, it is quite clear that this young and tech-savvy demographic is as crazy about and engaged with music as any previous generation."
But he added it was "clear that the financial gains are not necessarily feeding back to the creators: artists, composers and songwriters".
"How the music industry repositions itself here, and builds new mutually-beneficial commercial partnerships with technology providers remains the key challenge ahead," he added.
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