Per this thread (now locked).

Arriving in Auckland this weekend, I noticed that my SingTel phone had roamed onto NZ Comms at the airport, and held coverage til about Mt. Roskill.

A few observations:

- Inbound voice calls worked
- Outbound voice calls mostly worked
    - A call to a couple of NZ service numbers (083xxx) failed and had a very generic sounding voice failure message. Doesn't sound like much customisation has been done so far.
- Outbound SMS worked.
- Inbound SMS did not work. When I roamed onto VFNZ my SMS' arrived.
- Data services did not work.
- I did not get UMTS 2100 service, but it did show as EDGE available.
- SingTel does not show NZ Comms as a roaming partner for NZ, so no pricing information.

Just a datapoint, really.