Professor Alan Duffy, an astrophysicist from Swinburne University, says the phones are packed with valuable components such as gold, copper, silver and palladium that can be extracted and re-used.

He's the face of an industry-financed and government-backed campaign to motivate people to recycle their old phones.

Australians upgrade phones every 2.5 years and research shows there are 24 million old mobiles lying about, about five million of them broken and likely gathering dust in drawers, boxes, garages and cupboards.

"They represent a valuable stockpile of resources that can be recovered and re-used," Prof Duffy said on Monday

"We stash them in case we need them again or because we aren't sure how to get rid of our personal data, and because we know we can't just throw them in the bin," he said in a statement.

If every one of Australia's five million broken phones was recycled, it would salvage 9850 tonnes of mineral resources.

"We'd also save 1930 tonnes of CO2 emissions, which is the equivalent of planning 50,000 trees," Prof Duffy said.

Recycling an old mobile phone is now free and easy.

It can be dropped off at a participating MobileMuster retailer or one of 3500 local collection points.

Otherwise people can pop phones in the post by ordering a mailing satchel or getting one from Australia Post.

Australian Associated Press