Vulnerable people in society need more government help to make the switch-over to digital TV, media regulator Ofcom's consumer panel has said.
An estimated 63% of UK households have digital TV
Culture Secretary Tessa Jowell has announced the formal go-ahead for the switch-over from analogue TV.
Viewers would have their existing TV signals switched off by 2012, she said.
But Ofcom's panel said the help outlined by Ms Jowell for the elderly and disabled to access equipment for the switch does not go far enough.
The panel's report estimates there are approximately 4.4 million households in the UK who may be in need of the practical support scheme.
Among those qualifying for help at a "modest fee" will be households with at least one person over the age of 75, or someone with a significant disability.
Help will be given free of charge to households who meet the same criteria, but who also receive pension credit, income support or jobseekers allowance.
But the panel fear some people, particularly the elderly, will be at risk from being ripped off.
Colette Bowe, chairman of the Ofcom consumer panel said: "Many people rely on family and friends to help them choose and use complicated new TV equipment.
Analogue switch-off will start in 2008 and be completed by 2012
"People who don't have this type of support are in danger of getting ripped off by rogue traders and going without television when the analogue signal is switched off."
The report estimates that a scheme using local volunteers to provide practical help to those who need it could cost up to £110m.
In addition an estimated £270m would ensure vulnerable people have a set top box and aerial, it said.
The panel also called on the government to ensure pensioners who are entitled to free equipment actually receive it.
"Many pensioners who are entitled to Pension Credit won't get financial help with switchover because they don't claim this credit," Ms Bowe added.
Figures from Ofcom show that an estimated 63% of households in the UK already have digital television - up from 61.9% from the previous quarter.
Ms Jowell said many of those yet to switch over to digital "are exactly the people that the state has a duty to protect".