Horizon Research shows 6.4% of New Zealanders 18+ do not have a landline telephone at home. This rises to 19.6% among 18 to 24 year-olds; 18.8% for those earning $100,000 to $200,000 a year and 12.5% for those earning less than $20,000 a year.
Basic findings; if you’re poor, young, or rich, you’re less likely to have a landline. This is only going to head in one direction. Expect more bias in polls.