bazzer: With local number portability, am I able to take my number to a different exchange? The telecom website implies that:

"There are only a few occasions when you can't keep your local phone number when moving (porting) to Telecom, for example if you move house to one outside of your original local calling area."

Moving from Mt Roskill to Panmure is still within the same "local calling area" isn't it?

In which case the first 3 digits won't be indicative of location anymore? Sort of like 021/027 has less meaning now. It would be great to move to another suburb and keep my existing number.

bazzer: Then, what if when I move I change providers, and then change back again at a later date?

You could not port your number to a different carrier then back to Telecom to retain the same number; otherwise Telecom would just let you do this in the first place.

Secondly, switching to an alternative carrier does not automatically mean your number will be ported.

nzbnw

bazzer:  And if so, when (if) I later moved back to Telecom, why couldn't I keep my existing number under the local number portability (assuming I'm still within the local calling area, which I consider to be the Auckland 09 area, but maybe that's not what it means).