Apple has sold its billionth iPhone in key milestone for tech giant

Apple crosses '1B iPhones sold' mark

Apple has sold the billionth iPhone, CEO Tim Cook announced at an employee meeting in Cupertino, California, on Wednesday.

"iPhone has become one of the most important, world-changing and successful products in history. It's become more than a constant companion. iPhone is truly an essential part of our daily life and enables much of what we do throughout the day," Cook said in a statement.

Cook said that the billionth iPhone was sold last week.

"We never set out to make the most, but we've always set out to make the best products that make a difference. Thank you to everyone at Apple for helping change the world every day," Cook said.

Apple declined to comment on where the phone was sold.

— CNBC's Josh Lipton contributed to this report.