TPG has begun construction on a number of sites as part of its trial of fibre-to-the-basement technology, and revealed new detail about the metropolitan areas in line to receive services as it unveiled its half year results today.

Last September the ISP announced plans to roll out fibre to the basements of an extra 500,000 apartments across metropolitan Sydney, Melbourne, Adelaide, Brisbane and Perth, to expand the number of buildings connected to its existing fibre network.

In today's half yearly results presentation, TPG revealed it had commenced FTTB construction in Pyrmont, Ultimo and Sydney CBD in NSW; Southbank, Docklands and Melbourne CBD in Victoria; and Fortitude Valley and Brisbane CBD in Queensland.

It said it was live trialling the service with a number of customers, but did not provide further detail by the time of publication.

The controversial plan - which mimicks efforts by the Coalition to build a national broadband network - has drawn criticism from NBN Co CEO Ziggy Switkowski, who said the initiative had the potential to “severely impact" the NBN.

Earlier this month TPG put forward its case to be allowed to continue exploiting a legal loophole in federal anti-cherry picking legislation, which allows a network operator to compete with the NBN as long as they limit network extensions to existing networks (built before January 2011) to less than 1km, limit speeds offered to under 24 Mpbs, or allow others wholesale access to the network to offer retail services.

TPG’s fibre network currently covers around 1600 buildings and 3800km.

It argued in a recent submission to a review panel tasked with conducting a cost-benefit analysis of the NBN and a review of its regulatory framework that its FTTB plans would not threaten the NBN.

It said many of the 500,000 premises it was targeting would be entrenched HFC customers, and it only expected to secure a percentage of the remaining customers.

“The number of households who will obtain TPG FTTB will be insignificant compared to the number of households to be targeted by NBN Co,” it said.

The Australian competition watchdog and fellow ISP iiNet have backed TPG's argument that infrastructure-based competition would deliver the best outcome to end-users.

TPG today reported a 15 percent rise in net profit for the first half of fiscal 2014, to $90 million, and an 11 percent increase in revenue to $395 million.