Indonesia is the latest country to sign on to Google's Project Loon, a plan to deliver Internet access around the world from helium-filled balloons.

Google's parent company Alphabet Inc. signed a deal with PT Indosat, which is partly owned by the Indonesian government, PT Telekomunikasi Selular, and PT XL Axiata to test the balloons, Bloomberg News reported. 

Indonesia is a good testing ground because it's made of many islands that are difficult to link via cables, Bloomberg reported Project Loon leader Mike Cassidy as saying. It also has the world's fourth biggest population and 150 million residents still have no Internet access.

“In effect, Loon is building cell towers for the telcos,” Cassidy said, according to Bloomberg. “But the towers we’re building are 20,000 meters in the sky.”

The project started in 2013 with 30 balloons in New Zealand and Sri Lanka has also  signed on, according to the BBC. There are already tests in India.  About 300 balloons are needed to form a ring around the world, the BBC reported Cassidy as saying.