Could be some yrs ago, cannot recall recently but .. if we drive Wellington to Auckland or Dunedin to Queenstown are you garuranteed of continual coverage? Meaning 2G coverage. Don't need 3G fancy stuff everywhere. You know .. emergency calls as people need on the highways.
Re: the cost. Landlines are about $45/mo, prepay cellphones (even contract plans) are much cheaper. Are cellular cheaper to run than landlines (from a supplier's view)? I also recall Vodafone has a Home plan thing, this box at home and you get free unlimited local calls around your house's perimeter and it is cheaper than the landline.
Should mobile data then be cheaper than ADSL?