Want to convert my Netflix gift credit into a mobile phone credit
This is not possible, no.
Voucher cards and prepaid vouchers are two different worlds.
I'm not sorry I don't know. Such a Netflix card is only intended for Netflix
You can use the code m. M. After redeeming anyway, the amount will only be debited again when the credit has been used up. And then charge the cell phone with the money saved.
Otherwise you could trade with someone, but it can happen that you get ripped off if you don't know the people and give out your code on the Internet.
Do not quite understand what you mean at the beginning but would you have a tip how I can most surely swap with someone?
For me, Netflix debits via PayPal, but I can still enter voucher card codes.
The safest way to trade is with people you know well.