The Australian Competition and Consumer Commission (ACCC) has approved Telstra's proposal to vary the National Broadband Network (NBN) migration plan, saying it will provide retail service providers (RSPs) with a longer timeframe in which to migrate customers to the NBN prior to mandatory disconnection.

The migration plan details the process by which broadband and phone customers will be transitioned from Telstra's legacy copper network and hybrid fibre-coaxial (HFC) network to the fixed-line NBN.

"The changes to the migration plan offer further safeguards for telecommunications customers so they can maintain access to the services they value during migration to the NBN, provided they have submitted their NBN order in time," ACCC Chairman Rod Sims said on Thursday.

"These changes will allow retail service providers more time to complete their migration activities before managed disconnection, and are intended to promote a more positive experience for customers as they move to NBN services."

According to the regulator, the varied migration plan will improve arrangements thanks to being based in real-world experience of migration activities to date.

"The ACCC considers that Telstra's proposed variation reflects improvements to the migration process following greater industry experience in migrating customers," the ACCC said in its final decision [PDF].

"The proposed changes provide greater assurance and certainty to end users that they will not prematurely lose their voice and broadband services prior to migrating to the NBN. In particular, Telstra's proposed variation promotes the efficient and timely disconnection of carriage services from Telstra's legacy networks and seeks to minimise disruption to the supply of services to the extent that it is within Telstra's control."

The variations proposed by Telstra [PDF] included allowing additional time for all premises to be connected before mandatory disconnection takes place, as currently used by Telstra and NBN under interim measures; and for "special services" to be given an additional 12 months prior to mandatory disconnection when they are moved to a separate access technology under the multi-technology mix (MTM) NBN.

The first of the major changes sought by Telstra, concerning in-train order premises -- described as premises that are still waiting for their NBN service order to be filled after the disconnection date has passed -- saw the telco request that services should continue being supplied for up to 150 business days after the date has passed, rather than just 30 days.

Telstra also recommended NBN notify it of completed or cancelled in-train orders during three "test points": 60 business days, 90 business days, and 120 business days after the 30-day disconnection date.

The final notification date would then serve as the marker for when a premises would be disconnected by Telstra.

NBN supported Telstra's request, while rival telecommunications provider Optus raised concerns with the test points, saying they were "likely to have a detrimental impact on business customers who require complex porting and post-installation activities, creating a significant risk of managed disconnection occurring before the RSP has completed installation".

However, the ACCC approved the amendment.

"Telstra's modified in-train order proposal provides RSPs with a period of between 90 to 170 business days to migrate in-train order premises in the first 'test point' and up to 150 business days to migrate in-train order premises in the second 'test point'," the ACCC said.

"The ACCC considers that the proposed arrangements now promote greater service continuity and provide RSPs with suitable time to complete end-user installation, complex porting (where required), and post-install activities before managed disconnection."

The second of the larger amendments requested, regarding special services, saw Telstra put forward that if NBN changes its determination of the access technology being used to supply special services -- business-grade services, such as ISDN, data transmission, and remote telemetry -- within six months of the disconnection date for the premises' rollout region, an extra year should be added to the premises' disconnection date in order to mitigate the possibility of disrupting such services.

Again, NBN supported this change in its submission while Optus opposed it, arguing that it would "add another layer of complexity to an already complex disconnection process" by separating rollout by network technology being used. Telstra responded to Optus by saying the changes reflect the MTM model, with the ACCC approving it.

"The ACCC is satisfied that the proposed arrangements for special services are appropriate in a MTM NBN rollout model to promote the efficient and timely disconnection of services from Telstra's legacy networks," the regulator said.

Several minor changes were also approved by the ACCC: Altering the definition of a service area module to include 5,000 premises rather than 4,000 as outlined in the definitive agreements; updating the migration plan to include quarterly reporting, an obligation previously agreed to with the ACCC; and ensuring that the migration plan clarifies that the order stability period also applies to the HFC network as well as the copper network.

The ACCC had in May published a discussion paper on Telstra's proposal, seeking feedback on whether the migration plan should be amended to include Telstra's proposed changes, and whether they align with the migration principles.

The migration principles include driving the efficient and timely disconnection of services; reducing the possibility of disrupting the supply of services; providing wholesale customers with autonomy over decision making on disconnecting; and ensuring that wholesale services and retail services are disconnected in an equivalent manner.

In September 2014, Communications Minister cum Prime Minister Malcolm Turnbull began consultation to modify the migration process after the original May 2014 deadline to get residents off the legacy copper had failed. Three months after that deadline, there were premises in the first 15 regions "still subject to the migration process" as a result of poor coordination and communication between NBN and RSPs, and inadequate construction that prevented premises that had been passed by the NBN to actually connect to it.

Last June, the ACCC approved the migration plan seven months after Telstra and NBN had entered into a revised AU$11 billion deal allowing NBN to take ownership of Telstra's copper and HFC network assets. The modified agreement came as a result of the Coalition government's decision to move away from a full fibre-to-the-premises rollout to the present so-called MTM network incorporating fibre to the node (FttN), fibre to the building (FttB), and HFC.