Where are you located? Here in Taranaki we have a very innovative and customer orientated ISP in PrimoWireless. They have a growing network of transmitting sites that serve the difficult terrain around coastal Taranaki and also the rugged eastern hill country. Integrated VoIP service available at $15/month.
Other regions have similar providers that you can probably find here: https://www.broadbandcompare.co.nz/
Other regions have similar providers that you can probably find here: https://www.broadbandcompare.co.nz/