4 billion mobile phone numbers active
“The number of mobile phone subscriptions in the world will reach four billion by the end of the year driven by growth in developing economies, the International Telecommunications Union said Friday…The ITU stressed however that its estimate does not mean that four billion individuals each have their own mobile phone, as many people in developed countries have more than one…Continued progress in 2008 is chiefly due to the growth in major developing markets such as Brazil, Russia, India and China.” (Source)