My daughter left for Aussie last month. She has a Skinny number on a Kogan monthly plan but would like to keep the number active and have access to SMS etc for authentication of NZ accounts should she need it.

I've checked the major players for options but their sites only have prepaid plans for $4/$5 month or the usual monthly plans.

What am I missing not seeing the old "pay as you go, top up $5 a year" options ?