The global number of telephone lines has quadrupled to almost 4 billion in the past decade, largely driven by the ongoing mobile phone boom in developing countries, according to a recent United Nations report.

There were fewer than 1 billion fixed and mobile phone lines at the end of 1996, according to the UN’s International Telecommunications Union (ITU). Since then, landlines have show relatively slow and measured growth, while mobile services have taken off, showing “spectacular success” according to one of the reports authors.

The ITUs latest figures count 1.27 billion fixed lines and 2.68 billion mobile phone accounts worldwide. The number of mobile phone users, 61% of which now live in developing countries, has been sharply on the rise ever since customers in emerging markets realized that they could buy cell phones much more cheaply than wiring their homes for landlines.

China and India have shown the most impressive wireless growth over the past couple of years, adding 200 million subscribers to the global total in the first three months of 2007 alone.