New Zealand toll-free and premium numbers

[davemcginnzendesk]

There is an issue with New Zealand toll-free and premium numbers where 0508 numbers are not considered valid.
0900 numbers may be followed by either 5 or 6 numbers, but the 6 digit format is not considered valid.

voice-app(staging)> Phony.plausible?('+64508123456')
=> false
voice-app(staging)> Phony.plausible?('+6490012345')
=> true
voice-app(staging)> Phony.plausible?('+64900123456')
=> false