The consortium won its licence in 2007
Channel 4 has abandoned plans to set up three digital radio stations, blaming a slump in advertising revenues.
The broadcaster's chief executive, Andy Duncan, said the decision had been taken "very reluctantly", but admitted the enterprise had become unaffordable.
The first station, E4 Radio, was due to go on air next spring.
Channel 4 was part of a consortium due to open 10 stations and media regulator Ofcom said talks would take place to assess the future of the project.
It added that other radio operators, including the BBC, would be consulted "to secure a viable outcome which is in the interests of radio listeners and the industry".
Channel 4's withdrawal will lead to the loss of 15 jobs, but the broadcaster will try to redeploy the employees in other areas of the organisation.
Mr Duncan added: "We've pursued our radio plans in good faith and continue to believe DAB has a strong future and that we could make a return from radio in the medium term."
Channel 4 is expected to save £10m in 2009 by abandoning the stations.
Tim Davie, the BBC's director of audio and music, said the news was "disappointing for UK radio", but added he appreciated Channel 4's move in the light of the economic climate.
The BBC was looking forward to "driving further growth of the platform", he said.
The 4 Digital group was awarded a 12-year licence to run a digital radio multiplex in July 2007.
Channel 4's partners in the consortium include BSkyB, Bauer Radio and Carphone Warehouse.