The company said it can "absolutely guarantee" that customers will no longer suffer from the frustration of not having a proper mobile phone signal if they sign up to their Sure Signal box.

The Sure Signal box is a femtocell, a technology pioneered by a British company, Picochip. They are simple black boxes, the size of a paperback book, which plug into the back of a customer's broadband hub via an Ethernet cable.

They are, in effect, miniature mobile phone masts which amplify the reception within a 50 yard radius, ending so-called "not-spots" that blight parts of the country.

No changes to the mobile phones are necessary. All that is needed is a broadband connection, however the box will only amplify the Vodafone signal and will not help any other mobile phone customers suffering from poor reception in the house.

Guy Laurence, the chief executive of Vodafone in Britain, said: “No other network in the UK can ensure a great mobile phone signal in the home, because the Sure Signal is unique to Vodafone.

”Customers tell us it is life changing. If they live or work in a basement for example, the only way they may be able to get consistent mobile coverage could be with a Vodafone Sure Signal.”

The Sure Signal announcement from Vodafone follows a trial last year when thousands of customers bought femtocells costing £160, a high price for many consumers.

James Holland, editor of the gadget website Electricpig, said: "I think this is a bitt of a swizz. OK, £50 is a lot more reasonable than £160 but I am not sure why it is the consumer who should pay for a lack of mobile phone signal, rather than the phone company.

"I can see they will be a lifeline for some people who live in the middle of nowhere or in a basement, but I am just not sure about the price."

Femtocells not only should improve mobile phone coverage, but they also allow smart phone customers such as iPhone users to download far more data to their devices.

Ofcom, the telecoms regulator, has calculated that some parts of the country, notably Wales and Scotland have very poor mobile phone reception, with 61 per cent of these areas unable to receive proper 3G coverage – the modern mobile phone signal that allows data such as photographs and sports scores to be downloaded to phones.

Across the UK nearly one in five consumers – 18 per cent – regularly found they were in a 'not-spot' at work or home, with 91 per cent of small businesses occasionally suffering from poor reception.

Source:telegraph