Cell phone subscriptions worldwide are expected to reach four billion by the end of the year, the International Telecommunications Union said Friday, according to AFP. Growth in developing economies is credited with the surge in subscribers.

"Since the turn of the century, the growth of mobile cellular subscribers has been impressive," ITU said in a statement, according to AFP.

Cell phone subscriptions topped 3.3 billion by the end of 2007, and the growth is due mainly to markets such as Brazil, Russia, India and China.

"These economies alone are expected to account for over 1.3 billion mobile subscribers by the end of 2008," the ITU told AFP.

China became the biggest mobile phone market this year, surpassing the 600 million mark, while India had around 296 million subscribers by the end of July, AFP reported.

Click here to read the AFP report.