NBN Co is leaving progressively more premises unable to connect to its network for two or more years, new statistics from Telstra show.

Telstra, which is managing masses of disconnections from its copper network in line with its NBN agreement obligations, revealed a growing number of premises that can’t order an active NBN service.

Disconnections from legacy copper to NBN occur in “waves” - essentially months.

There is an 18-month window in which ADSL users must move to FTTN/B/C before their legacy services must be switched off, and this can be extended for a further six months, Telstra said.

However, Telstra revealed that “thousands” of premises a month still can’t connect to the NBN after this two-year migration window elapses.

“Commencing with disconnection wave 51 (with ready for service [RFS] dates for the relevant regions of approximately August 2016), the number of premises that remain non-serviceable … 24 months post-RFS has increased significantly,” Telstra said.

“Where previously there were small numbers for every wave that could be managed individually, the numbers have increased to multiple thousands of premises per disconnection wave (per month).

“Since February 2019, on a month-by-month basis, Telstra and NBN Co have agreed to further extend the disconnection obligations for these premises when they remain non-serviceable, firstly by 150 business days, then by another 150 business days.

“Currently there are approximately 8000 premises in this category, some of which have been non-serviceable for up to and beyond 36 months.”

Telstra said it has to manually manage this growing number of premises to ensure they don’t get disconnected from ADSL services while in NBN limbo.

The issue has been bubbling through 2019 as Telstra continually filed for special regulatory clearance to prevent mandatory disconnection of these services in further allotments of 150 days.

However, it was not clear why this was occurring from the brief public regulatory filings.

It appears that the premises being left behind are part of a number NBN Co has been touting recently for premises that may not be ready to connect in mid-2020 when the network is due to be complete.

These premises were defined as “complex installations” in NBN Co’s most recent corporate plan.

Telstra has raised concerns that NBN Co is not putting enough resourcing behind the growing issue.

“Telstra is concerned that, despite these growing numbers, NBN Co is not dedicating sufficient resources to delivering serviceability to these ‘left behind’ premises, and has not publicly recognised this issue or provided any sort of plan to address the long tail of non-serviceability,” it said.

The telco wants specific serviceability rules to be added into a draft final access determination (FAD) on wholesale service standards for NBN Co, which the Australian Competition and Consumer Commission (ACCC) is evaluating.

It wanted assurance for its own purposes, as well as for customers, who often confusingly received marketing offers to connect when they couldn’t, resulting in retail service providers (RSPs) placing orders for unconnectable services.

Telstra wants a process established whereby users can request connectivity and a serviceable line is then delivered in 30 business days.

It also wants NBN Co to “publish a weekly report setting out every Location ID (LoCID) in the long term unserviceable category with estimated dates for each premises to be made serviceable.”