Flip has two Unlimited Calling Packs.
Call National landlines and NZ Mobiles as much as you like for just $10 per month.
It's one hour per call, 20c p/min after that. To avoid paying the p/min charge simply hang up before the hour is up - call back if you want to keep talking.
Kiwi & International
For only $15 per month you can get unlimited calling to 85 destinations including National landlines and NZ mobiles. Pretty sweet huh.
Again, it's one hour per call, 20c p/min after that.