Necessity is the mother of invention, they say, and Jan Chipchase spends his time seeking out the world’s poorest people and finding out what they have been inventing. The results are amazing in their ingenuity and directness.

Chipchase, an anthropologist, says: “I travel to the ends of the earth to find out what people actually do with their mobile phones.” Some of the research is into the most basic aspects of modern behaviour. What we carry when we go out of the front door, for example.

He says: “What are the three things people carry? They used to be keys, money and watch. Now they are keys, money and a mobile. The reason is that these are the things you need for survival, and the mobile is a great recovery tool.”

This is not just true in the West but throughout the world, where the mobile is becoming an essential tool for billions of people who until now were excluded from the world economy, such as rural farmers in Africa, illiterate people in India and billions of people who are not normally seen as mobile phone addicts.

What is even more remarkable is that people on the margin have much to teach us in the developed world. Chipchase says: “About 799 million people are illiterate, how do they manage?” He went to India to find out. Basic mobile phone use is easy, he discovered, because illiterate people compensate with excellent memory skills. Show them the “answer” key once, and they know how to reply to calls. They soon pick up dialling by comparing written numbers with those on the phone and they are adept at getting help.

The work with illiterate people may lead to phones that are easier for us all, Chipchase believes. “If we find solutions for illiterate people we will find solutions for the rest of us. They are our lead users. What if you could just pick up the phone and say ‘I want to speak to...’ and it just did it?” Already, insights gained have influenced the design of one of the most popular handsets in the subcontinent. “The Nokia 1100 in India was heavily influenced by work with illiterates.” Another deprived group, the blind in India, have proved to be a goldmine for insights into phone use.

“A blind mobile phone user can give us insights into how people can use a phone who cannot see the screen. We met a blind man who has set a customised ring tone for each of his associates so he knows who is ringing.”

In Uganda Chipchase found that people with little education and less money have been incredibly creative in devising ways of adapting mobile technology to their way of life.

To keep phones going an informal repair culture has sprung up, with self-taught engineers sitting on stools in the market. “Repairmen can strip and rebuild most models with little more than a screwdriver, a toothbrush and knowhow.”

Coverage has been expanded by a network of home-made phone kiosks owned by local entrepreneurs, each containing a mobile. A wire strung to a nearby tree forms an antenna that can pick up a signal from a base station well beyond the official range.

The owner of the kiosk offers “step messaging” — if the caller wants to send a message to someone further up country, a messenger takes it the final distance on foot. The mobile is even used to transmit money, which very much in demand from city workers who want to send funds home.

It is called Sente. The sender buys a mobile phone topup card, but instead of topping his own phone up he tops up the phone of the kiosk owner nearest home, who passes the money on to his family (minus his commission, of course).

Sente has weaknesses and relies on trust, but is better than having to take a two-day trip home. “Everyone who has a phone, has an ATM,” Chipchase says. For years people in the West have talked about mobile phone ATMs. In Africa it is already a reality.