Those days are long gone when placing a telephone call meant simply picking up the receiver and asking the operator to patch you through. Modern cell phones require users to navigate a series of menus to find numbers, place calls or check messages. Even the most tech-savvy may take weeks to discover some of the more arcane multimedia functions. Imagine the difficulty for someone unable to read.

That is the challenge for mobile communications companies aiming to branch out into developing countries. The prospects are alluring: according to the GSM Association, a global trade group, only about one third of China's vast population and about one tenth of India's use cell phones. But selling to poor rural areas is not likely to happen with a marketing version of "plug and play." Most potential buyers have little exposure to anything other than simple electronics. Reading through a series of hierarchical menus and pushing buttons for multiple purposes would be new concepts for such customers.