fibre, exchange space and ducts to NBN Co. as part of the agreement, Telstra would not be able to market their mobile network as an alternative to the NBN for a number of years. The agreement with Telstra required that the copper telephone network be decommissioned in an area 18 months after optic fibre is ready for service and that new connections were to be made to the optic fibre network and not the copper network. In some cases, premises have been left without service due to lengthy delays in establishing NBN connections. Telstra advises the use of the mobile network for phone and internet in these cases. Agreement with Optus (23 June 2011) NBN Co signed an agreement with Optus over its hybrid fibre-coaxial network estimated to be worth post-tax net present value. The ACCC—whose approval is required before both agreements take effect—raised concerns about the clauses being anti-competitive. First release sites (2011) Five areas comprising around 14,000 premises were chosen as the 'first mainland sites', each representing rollout challenges the NBN was expecting to face during an Australia-wide rollout, with the first services going live on . commenced on , Armidale was the first site to officially launch on with 2,900 premises included of which 90% did not opt out for connection. Kiama Downs and Minnamurra was the second site to officially launch, following Armidale on . Approximately 2,350 premises were passed, of which 80 per cent did not opt out for installation. Brunswick had the lowest installation rate at the time of its official launch: of the approximately 2,689 premises passed, only 50% opted for installation. Aitkenvale and Mundingburra followed Brunswick on with approximately 3,100 premises passed and 63 per cent did not opt out for installation. Willunga was the fifth and final 'first release site' to officially launch on with approximately 940 premises passed and 91 per cent did not opt out for installation. These figures are for passive installation of a dark fibre to the premises. To activate it residence need to purchase a service from an RSP. Furthermore, following the low take up rates in Tasmania, the government has adopted an opt-out model in which users are assumed to want the service unless they explicitly opt-out. Thus passive installation figures may be quite different from the proportion of residences that actually use the NBN service. Second release sites Fourteen second release sites comprising 54,000