As far as I know it should be okay.
"NBN Co will let you know by direct mail your region’s ‘ready for service’ date. Once NBN has announced your area is ready for service you will have 18 months to move your landline phone and internet services to the new NBN network by placing an order with your preferred service provider.
Any services you do not cancel or move to the NBN will be disconnected soon after the end of the 18 month period.
If you do not want to move to the NBN, consider asking you preferred service provider about other options such as mobile phone or mobile broadband that are available to you.
Some homes and businesses get their internet and phone services from companies that use networks that compete with the NBN. If you’re with one of these companies you don’t have to move to the NBN and your services won’t be disconnected. Check with your provider if you need to move."
I found this on: ACCC's site.