In the spark submission (Slide1), they provide this graphic, Vocus is one of three companies mentioned with extensive backhaul, Chorus is like NBNCo i think and just the last mile. I believe there are is also some other seperate regional bits and pieces.
For Trustpower or 2Degrees to be on the same level as challenge Spark and Vodafone, they will really want our infrastructure. Same with Telstra, who could perhaps consider rolling out mobile in NZ, but i think that would be a harder ask.