National Broadband Network (NBN) CEO Bill Morrow has said the company is looking into several options to improve its satellite connections following widespread complaints about congestion and slow speeds.

In response to requests from Communications Minister Mitch Fifield and Regional Communications Minister Fiona Nash to improve the Sky Muster satellite service, Morrow said NBN is considering deploying a third satellite, piggybacking off a third-party satellite, building more towers, or improving the tech on its existing two satellites.

"[A third satellite] is one of the options that we are looking at to satisfy Minister Fifield and Minister Nash's requests," Morrow told Senate Estimates.

"We will look at enhancing the existing technology with the two satellites that are up there today; we will look at a third satellite to see if that's feasible; we will look at other satellites that are third party that will be up in the sky that maybe we can leverage those satellites to get more capacity; we will look at getting some other towers to relieve the congestion of the satellite beams that are coming down.

"There's nothing that is sacred here. We are looking at anything and everything that might be feasible to offer more capacity."

Sky Muster has been subject to widespread criticism, with the federal opposition party last month saying the satellite service should be subject to an independent expert review, as the installation issues, data caps, outages, and lack of transparency between NBN and its retail service providers (RSPs) need to be examined.

This was despite Labor being responsible for ordering NBN's two Ka-band satellites, which were labelled as unnecessary "Rolls-Royce" satellites by then-opposition communications leader Malcolm Turnbull, who has since revised his opinion to "world class".

Under NBN's 2017 Corporate Plan, between 200,000 and 250,000 premises will receive a satellite connection, although 400,000 premises are eligible, with customers capped from using more than 150GB per month -- separated into 75GB off peak between 1am and 7am and 75GB on peak, with 50GB extra for distance education students, and has a maximum download speed of 25Mbps -- and on 25Mbps maximum speeds.

Australia's states and territories have similarly criticised the satellite service, with the South Australian government saying Sky Muster should be a "last resort" because it is a form of geographical-based discrimination; the Queensland government arguing that use of "lower-grade" NBN services for those living in regional and remote areas of Australia is unacceptable and inequitable; and the Northern Territory government slamming the "technically inferior" satellite service.

In January, NBN revealed that there had been 31,007 reschedules of Sky Muster service installations between April 2016 until October, caused mainly by technician issues, customer issues, weather, network issues, and non-standard installations.

The average closure time for complaints was 21.4 days during October last year, with 520 complaints between April and October.

According to satellite RSP Clear Networks, these complaints are exacerbated by the lack of information on connectivity issues given by NBN to RSPs, which leaves customers at the mercy of NBN's 10-day turnaround.

Morrow said on Thursday that in total, NBN missed 82,552 appointments in 2016.

Service class zero

Labor has also criticised Morrow's responses in Senate Estimates this week on premises that have been classified as being "service class zero" -- premises that cannot connect despite the rest of their region being able to order NBN services.

"We let the retailers know which homes are not ready for service," Morrow said, adding that as the wholesaler, NBN does not contact the consumer directly. Consumers could also check their forecast connectivity timeframe by using NBN's online address checker, he said.

While it could take up to two years for such service class zero premises to be connected, it is a 6.5-month wait on average, Morrow said.

"It could be a year, it could be two years, the point is that not every home is going to get done overnight, but all homes will be done by the year 2020," Morrow told Senate Estimates on Thursday.

"It's really unfortunate that if somebody has a complex area, that requires this to be toward the end of the build. It is what it is, but again everybody will get taken care of by the year 2020."

Shadow Communications Minister Stephen Jones, however, criticised NBN for not notifying customers when their premises have technical obstacles preventing them from being connected.

"In Senate Estimates last night, NBN CEO Mr Bill Morrow said that NBN doesn't tell customers about this but relies on customers using their website's address checker. As a result, nobody is taking responsibility for being honest with these customers and telling them that they are in a different situation that requires detailed work," Jones said on Friday.

"These customers, known to NBN as "Service Class 0", are growing in number, and this month there are around 200,000 premises left behind."