6 and 8 digit mobile number support for NZ (+64)

I got a problem.
Mobile number "+642142xxxx" wasn't plausible.

Wiki says that NZ mobile numbers starts with 02 can have from 6 to 8 digit number
http://en.wikipedia.org/wiki/Telephone_numbers_in_New_Zealand

The same here: http://www.tnzi.com/about-us/numbering-plan/
"Mobiles/pagers: 2-digit code plus 6-, 7- or 8-digit numbers"

6-digit format:
http://forums.whirlpool.net.au/archive/1542609
"From a mobile: +64 xx yyy zzz"

I'm not sure about correct 8-digit format, so just set it to xxxx yyyy. I'll ask one guy from NZ about 8-digit phone number format and change it if it will be required.