Traditional analogue radio stations could be facing extinction under proposals put forward by the communications regulator Ofcom.
Ofcom says any switch off would be a matter for the government
It is suggesting a review of AM stations in 2009 and of FM services in 2012, or when digital use accounts for 50% of the total, whichever is sooner.
It also wants analogue licences, up for renewal from 2009, to be extended - but with a two-year notice of termination.
Ofcom says the analogue bandwidth taken up by radio could be put to better use.
Costs and benefits
The regulator is predicting 90% of all radio listening will be via digital platforms by 2017 and is launching a consultation on how best to use the analogue signal.
Current licences are set to expire between 2009 and 2027, depending on the date of issue.
An Ofcom spokesman said: "There is no date set for switching off analogue radio signals but with the increased use of digital we need flexibility in the spectrum.
"Any such changes are a matter for government and parliament but they may wish to consider how to allow Ofcom to achieve common end-dates for all FM and AM licences."
It added: "Any reviews would include a full assessment of the costs and benefits, taking into account the needs of consumers, including the most vulnerable members of society."
Ofcom believes the freed-up spectrum could be used for mobile television, more digital radio, more community radio services or other new technologies.
The consultation will end in June.