Hi all, 

This may be a dumb question but I have no clue the answer. 
A friend came to me and they are currently on an Open Plan with One NZ. 

They have just ordered the Mighty Moblie $20 per month and it will take a couple of days for that sim to arrive. 
They want to keep their old mobile number which seems to be fine from the comments with Mighty Mobile. 
However what they asked me was if they will need to cancel their One NZ open plan or will it auto cancel when the phone number is ported over to Mighty Moblie?

I have no clue?

I can warn them about any over lapping periods of the One NZ plan, however at a lost of what happens with One NZ, their website was no help other than call them.

Was wondering if any GZ had experience of what they may need to do or what will happen. 

Thanks.