The company building the National Broadband Network (NBN) is about to launch a trial of an alternative network in New South Wales and Victoria.

Over the next few months, NBN Co will test a fibre to the node (FTTN) system with Telstra in Woy Woy in regional NSW, and Epping near Melbourne.

After the federal election in September, the Government directed NBN Co to replace the fibre to the home (FTTH) rollout with a cheaper alternative.

The FTTN option sends optical fibre to street cabinets and then uses copper for the last part of the connection to the home.

In an FTTH network, optical fibre runs to all homes and businesses.

FTTN is ultimately a slower network but the Government says it can be rolled out faster.

Labor's FTTH rollout hit trouble, particularly in apartments, because of the construction and administrative difficulties caused by having to pull optical fibre cables to every unit.

Tens of thousands of apartments could not connect to the NBN, but were counted in the rollout figures because technically the network 'passed' their premises.

To resolve that problem, NBN Co is also running a trial in Melbourne to test a network that takes fibre to the basement and uses the existing wiring to connect.

The company will make the announcement during the release of its half-year financial results at an event in Sydney today.