I am going to be in New Zealand for 5 months. I have an IPhone 8 on an AT & T Plan. What do I need to be able to communicate with the USA from New Zealand and not pay a fortune?
Check with AT&T if the phone is unlocked, if it's unlocked then you can buy a VodafoneNZ SIM Card here (TravelSIM would be good).
If it's not unlocked, ask them to unlock it, or you'll have to use your AT&T connection roaming over here.(Probably very expensive to do that for 5 months).
Or stick to wifi and over the top apps (eg whatsapp / viber / iMessage etc) (Probably not very convenient for 5 months)
So best bet to get handset unlocked by AT&T and buy a VodafoneNZ SIM here.