If you are only paying $30 a month for the NBN, don't expect a super fast experience, especially at peak hours, when you are most likely to actually want to use the internet.

Instead, customers paying only $30 per month are part of the "land grab" among telcos trying to get as many customers as possible out of the scrum as millions of Australians transfer from a Telstra-owned phone network onto NBN Co's infrastructure, according to NBN Co's chief executive Bill Morrow.

"You should expect a 12 megabit per second [Mbps] top line speed, and the actual speed at busy hour will depend and vary by retailer but I would not expect that speed to remain at 12 Mbps if you are paying $29," Mr Morrow told Fairfax Media.

He recently told a parliamentary joint committee the slower 12 Mbps product "was never designed for broadband" and its widespread use may be why so many people complain about their experience on the NBN.