In a land where television has long been a basic necessity of life, millions of people may find themselves without access to television Friday when the US switches from analog to digital broadcasting.

The change is part of a long-delayed update in the allocation of the wireless spectrum, which is used to broadcast everything from TV signals to mobile phone services and emergency radio traffic.

It is designed to free up valuable frequencies previously used by television stations to broadcast their signals and which will now become part of the information superhighway on which users of iPhones, Blackberries and other smartphones and mobile laptops will increasingly get the information they need to stay connected 24/7.

There are advantages and disadvantages to watching TV through these converter boxes. Firstly, the boxes can be a hassle to install - especially for those not fond or adept at moving their televisions and dealing with the mass of cables in the back. Numerous companies do offer installation services for the new converter boxes but these services bump the cost of conversion far above the $40 value of the coupons.

In some areas the digital signal can be better than analog - though in others it can be worse or even nonexistent. Many digital boxes do offer a useful viewing guide - though some elderly people complain that learning how to navigate the system with a new remote control is fiendishly complicated.

'It has all been a nightmare, and it's very, very upsetting,' said Frances Lim, a 72-year-old woman in San Jose California. 'We don't have money for cable or satellite and were very happy with the few stations we have been getting for years. Now we have to change. I didn't know how to do it. Luckily my grandson helped me. But I'm still learning the new remote control.'