As an audio nut I noticed this yesterday.
It has been a nice surprise in the last few days to be getting wideband audio codec calling in Invercargill between Spark mobile customers.
I noticed calls even to Palmerston yesterday were wideband as well. A good 8-10KHz or better.
We're probably one of the last towns to get it but it sounds great. So much easier to hear people when half their audio frequencies aren't cut off.