[LINK] NBN & POTS

[David Lochrin]

On Wednesday 13 September 2017 at 15:29 I wrote:

> However the POTS service continued to be available right up to the time I switched on the modem, and there was no background VDSL noise.  Can any Linker please explain how can this be so?

To partly answer my own question, there's an NBN option known as voiceband continuity or passthrough which offers hints.  See for example the link to the Interim Continuity Agreement at the bottom of http://www.nbnco.com.au/sell-nbn-services/supply-agreements/continuity-licences.html

My reading is that a party can notify NBN Co. it has a continuing requirement "for the use of the voiceband spectrum (100Hz to 4kHz) of all or a part of the Unconditioned Copper Sub-loop" and then "NBN Co will provide a VPL by utilising passive filtering to allow signals in the voiceband spectrum of the relevant NBN Co Copper Line (100Hz to 4kHz) to pass through and block signals above the voiceband spectrum using a low-pass filter in a splitter/combiner."  ADSL Services will be permanently disabled.

It's described more clearly on page-11 of the Telstra document at (long URL, it's a cached document) https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjbwKTCyaPWAhXCTrwKHQ99CVkQFggmMAA&url=https%3A%2F%2Fwww.telstrawholesale.com.au%2Fcontent%2Fdam%2Ftw%2Fnbn%2FDocuments%2Fservice-withdrawal-notification-mar17.pdf&usg=AFQjCNEY8qpXtioMFHR56IPW_7VPlqm91Q

QUOTE
DISCONNECTION OF OTHER SERVICES PROVIDED ON THE SAME COPPER LINE
Jumpering on a copper line (for both FTTN and FTTB) results in disconnection of all copper services provided over that line (except where Voiceband Continuity is provided – see “Continued provision of voice services” below).  [...]

CONTINUED PROVISION OF VOICE SERVICES
Retail and wholesale customers have the option of a partial migration to the nbn network which will allow the current service provider to continue to supply circuit switched telephony services on the Telstra copper network.  If this option is requested by an end-user, nbn co will enable Telstra’s continued supply to its wholesale customer of the voiceband on copper to the Premises (Voiceband Continuity).
UNQUOTE

So it seems NBN Co. can provide POTS voice in the 100 Hz to 4 KHz spectrum concurrently with VDSL2 data, though whether this can go beyond the 18-month complete cutover of an area is unclear.  I see Netcomm even sell the appropriate filter-splitters.  I presume this is part of the explanation for my original question.

Or does everybody know this already?

David L.