The company rolling out Australia's broadband network has struck deals with six construction companies to help build it.

NBN Co has signed deals with Lend Lease, Broadspectrum, Fulton Hogan, Downer, ISGM and BSA, to help meet a target of connecting eight million homes and businesses by 2020.

It is understood that the total value of the six deals is about $300 million for the first year, with further work to be determined by the progress of construction.