TV viewers in Wales, the Border and West country ITV regions could see analogue signals switched off within four years under a UK-wide timetable.
Viewers will need digital or satellite TV after the switchover
Media regulator Ofcom has said the UK can only be fully digital by 2012, the UK Government's target date, if it switches over region by region.
The switchover would need to begin in 2008.
The government said no firm decision on the timetable would be made until consumers' interests were protected.
The phasing in of a digital-only service would end with the analogue signal being switched off in the Channel Islands in 2012.
Currently, 60% of households in the UK have digital TV.
Digital terrestrial signals reach 73% of UK households, but a significant increase in coverage is not possible until analogue is shut down.
DIGITAL SWITCHOVER BY ITV REGION
HTV Wales 2008
West country 2008
HTV West 2009
Scottish TV 2009
Tyne Tees 2011
Ofcom's proposal, published on Wednesday, has been submitted to the Department for Culture, Media and Sport and the Department of Trade and Industry.
In a statement, Ofcom said: "The actual year in which switchover begins and regions subsequently convert remain a matter for government to determine as part of its overall switchover policy.
"Ofcom remains committed to the earliest practical switchover policy, while recognising the need to take proper account of the interests of viewers and other key parties."
To continue to receive television after the switchover from the analogue signal, viewers in digital-only regions will have to connect all their TV sets to a digital TV service, via Freeview, cable or satellite. In most cases, that would require them to buy a receiver box and possibly to upgrade their aerial.
Each region is expected to take six months to convert, giving households time to switch to digital cable, terrestrial or satellite.
Which? has warned the proposed timetable will force consumers in some regions to switch against their will within three years with costs of up to £300 - or lose out on TV altogether.
'Highly technical project'
Allan Williams, senior policy advisor for the consumers' rights body, said: "The government must keep its promises and should not switch off analogue TV unless the digital TV option is available and affordable to all.
"Vulnerable consumers, especially the elderly and socially disadvantaged, may not want the extra channels and the burden of the cost that digital will inevitably bring."
A statement from the UK Department for Culture Media and Sport said it wanted to make sure some groups were not left behind by the switchover to digital.
The statement read: "Digital switchover is a huge, complex and highly technical project.
"Switchover is very much work in progress and this is a useful indicative analysis of the best way to switch to digital TV region by region.
"We will make no firm decisions on the timetable until we are satisfied that the interest of all consumers, including the most vulnerable, are appropriately protected."