The migration of tourists comes mostly in the summer. The hotels, B&B's, restaurants, etc. in the area thrive on passersby. However it is a different story in the winter. Nearly the entire area is buttoned up and quiet.
If you are traveling through in the winter, it is best if you are looking for gasoline, general store, hotel, etc. that you begin your search before the sun goes down because you may find yourself in a very dark and lonely town.
Throughout most of the Catlins NP, we had no cell phone coverage. And if we did, it only lasted long enough to initiate a call, not to complete it.
If you are traveling through the area, plan to be disconnected for the duration.