US-based Iridium Communications Wednesday announced plans to launch a new fleet of satellites for global voice and data communications with Space Exploration Technologies (SpaceX).

The 492-million-dollar contract is the largest single commercial launch deal ever signed, the companies said, and will allow the telecoms firm to put up a new generation of low-orbit satellites with more capacity.

SpaceX's Falcon 9 launch vehicle will carry multiple Iridium NEXT satellites per vehicle from Vandenberg Air Force Base in California between 2015 and 2017.

Iridium said it may contract with at least one additional launch services provider.

"This is the third major building block on the road to Iridium NEXT," said Matt Desch, chief executive of Iridium, which provides phone communications in remote parts of the world.

"SpaceX has combined the best of aerospace and commercial best practices to design reliable and cost-effective access to space, and Iridium will be the beneficiary of that effort."

SpaceX expects to work with the US space agency NASA to transport materials to the International Space Station and possibly astronauts as well, in the wake of cutbacks in the US shuttle program.