"The mobile phone has become the most essential work item for Theuri, a Kenyan plumber, electrician and small businessman who, like so many others in the East African nation, makes a living from various different jobs at the same time.

Thanks to an explosion of growth in the mobile phone industry in Kenya over the past five years, Theuri says his plumbing-electrical business has grown by about 50 percent.

He also operates a community payphone via the mobile network and further cashes in on the boom by charging batteries for a fee. "Mobile phones have helped me very much," Theuri said.

"Sometimes I receive as many as five calls a day for different jobs. Were it not for mobile phones, jobs would have been very minimal. With the phone, I am well known."

Theuri says his phone number goes around by word-of-mouth from satisfied customers.

He is among thousands of Kenyans, many of them poor, who have taken advantage of the phenomenal mobile expansion to ease the way small businesses operate.

Painters and masons now advertise their numbers on trees by the roadsides in Nairobi. In the past, they would have sat outside hardware shops looking for work from people who have just bought nails, cement and other building supplies."