NBN Co has revealed 1.3 percent of premises in its fibre-to-the-node (FTTN) footprint - at least 15,000 in real terms - don't reach the government’s minimum 25Mbps peak speed promise.

It’s the first time such a figure has been released, providing an indication of the number of premises that will need to be moved to a different access technology in order for NBN Co to meet its statement of expectations.

The network builder said that “as at 9 November 2018, the proportion of FTTN connections achieving speeds of less than 25Mbps after coexistence is 1.3 percent.”

Coexistence refers to an 18-month window provided for customers to shift from ADSL to FTTN.

To prevent newer FTTN connections from interfering with adjacent ADSL services during this time, certain settings are put in place that prevent NBN Co from maximising the speed of the FTTN services.

Once the coexistence period lifts and VDSL vectoring is optimised, FTTN users are said to see peak speed capabilities increase by between 5Mbps and 10Mbps.

However, it has always been known that a percentage of the users impacted during coexistence would not see enough improvement to make FTTN a long-term option, meaning NBN Co would need to give them an alternative access technology.

The company has previously pointed to a mix of potential access technology replacements.

NBN Co confirmed overnight that it still used multiple options to bring underperforming premises up to minimum speeds.

“As NBN Co has confirmed on previous occasions, if a premises doesn’t achieve the required minimum peak speed of 25/5Mbps, then a design review is conducted to validate the most viable technical solution to remediate the location,” the company said.

“NBN Co may construct a micronode, or use other technologies such as FTTP [fibre-to-the-premises], and in the future FTTC will also be a solution available to deploy.”

NBN Co sporadically releases numbers on underperforming FTTN lines.

The last major release of these numbers was in August last year when it was revealed six percent of FTTN premises saw peak speeds below 25Mbps; however, at the time, it was unclear what proportion would have their problems resolved once coexistence ended.

Quantifying the impact

It’s still not clear exactly how many premises the 1.3 percent represents, but some calculations are possible.

iTnews understands that approximately 50 percent of the FTTN/B footprint is now out of the coexistence period.

Based on the number of activated premises - 2,370,000 - with half of those outside coexistence, 1.3 percent would be the equivalent of about 15,405 premises.

Using instead a ready for service number, the 1.3 percent climbs to around 25,092 premises.

Extrapolating that over a longer period, NBN Co expects to have 4.7 million premises ready for service using FTTN/B access technology by FY22.

If the 1.3 percent figure was to carry through to the end of the rollout, about 60,000 premises in the FTTN footprint could ultimately be in line for a different access technology to allow NBN Co to meet its stated requirements.

NBN Co said that "once coexistence has ended for a service, NBN Co will accept service incidents where a service operates below 25/5Mbps, noting that the cause of underperformance may be internal wiring or other conditions which are out of NBN Co’s control."

The company has previously built a diagnostic tool that it uses to check for in-home wiring faults, which could cause line speed fluctuations in the FTTN/B footprint.

Other FTTN numbers

NBN Co also published other numbers on its FTTN/B rollout.

It said that 84,930 premises in the FTTN/B footprint are currently classified as unserviceable (the former ‘service class zero and equivalent’ measure).

The company had 23,767 FTTN nodes operating as at November 12, out of a total of “27,000 to 28,000 FTTN nodes” it expects to deploy over the life of the project - though it noted the final number is still “subject to ongoing network planning and serviceability requirements.”

In addition, NBN Co said it had so far deployed 2845 compact sealed DSLAMs - also known as micronodes - with each serving an average 35-40 premises, meaning at least 100,000 premises in total are served in this manner.